Color-changing Chrysoberyl or Alexandrite is perhaps the most challenging gemstone variety for any buyer (on- or off-line).
Given its price, it is, next to Padparadscha, also the most faked gem on the internet.
The usual trick is to take two photos of a plain Chrysoberyl and then, with a click of the mouse, change one photo into red and the other one into green, re-name it "Alexandrite" and raise the price eightfold.
Less scrupulous, but still a scam, is to take a color-shifting Chrysoberyl and tweak the color-shift into a color-change; and then raise the price fourfold.
Finally, when legitimate Alexandrite refuses to be photographed correctly (or somebody dreads the extra work) people may re-produce the actual colors digitally. Some argue this to be OK in some cases but 100% trust and confidence in the seller is then required. Since such trust is rare the challenge of buying Alexandrite online lies in detecting digital coloring.
Here are some hints:
1. Pure green to pure red color-change has never been found in Alexandrite, much less photographed. If you see such a 100% color change on photo you better move on.
2. Average, yet still expensive, quality Alexandrite will often look blurred on photos. Day-green will be mixed with blue or yellow and/or brown, while purple is diluting the red or is even the dominant color at night. Such quality may still be rightfully called Alexandrite but it needs to backed up by a full gem report including:
a) That it is Alexandrite (not only chrysoberyl)
b) Defining the two colors
c) Judging the degree of change e.g. moderate or strong
Without certificate photos of Alexandrite are even less conclusive than those of padparadscha or ruby.
As always: Never buy without certificate (aka report).
3. Most traders will (or should) show day and night images. It is good and normal to detect the opposite color (e.g. some red in the green day-light, or some green-blue in the night photo). Exceptions exist but they are amongst the most expensive materials on earth.
4. It is theoretically possible to shot day/night images with two different light sources but 100% identical positioning, and thus identical luster and light pattern in both photos. However, such an identical light pattern in both day and night image are a good reason to suspect digital coloring. Individually shot day and night photos will always show different light pattern.
As far as inclusions, windows, cutting, brilliancy, cat's eye, crystal etc. are concerned Alexandrite is no different from other Chrysoberyl's.
Below is a legendary 8 carat Alexandrite cat's eye.
These are precision cut as well; and yet have flaws or are darkish:
Note: High-end gemstones in precision cut must look absolutely perfect on photo.
You can not be too critical here (but you will need a healthy budget). The best gems of each class get their first cut close to the mines and not many gems are, or can be, re-cut into perfection later.
Precision cutting needs size and availability; both are rare attributes at the top.
What constitutes a precision cut?
- Facets are exact and meet in one place - Symmetry and order in every dimension - Flawless polish - Maximized brilliancy
A pro-cutter can add many more topics but these are the basics which should be visible in any image.
Here are some examples of high-end precision cut gems:
To qualify as true Padparadscha, a natural sapphire must show orange and pink at the same time.
Here we may distinguish two forms of Padparadscha:
Pink and orange merge throughout the stone. The eye is puzzled with the melting color equilibrium. Some might perceive more pink, while others see more orange. Fascinating especially when a natural gems shows more pinkish orange in tungsten light, while being crispy orange pink at day.
Pink and orange are separated. An orange sapphire with pink areas also qualifies as true Padaparadscha (and the other way around). Though Pads with thoroughly merging orange and pink are even higher priced than those with "simple" color zones, the latter can also make very beautiful gems. Color zoning of this type is also an indication that you are looking at a natural unheated Padparadscha. Nevertheless you should insist on a certificate.
Additionally Padparadscha connoisseurs distinguish between "pinkish orange" (orange is the more dominant color) and "orange pink" (pink being more dominant).
Thus, we may define four types of natural Padparadschas as shown below:
1. Orange Pink (merging orange into pink)
2. Orange with pink (pink zones in an orange stone)
3. Pinkish Orange (merging pink into orange)
4. Pink with orange (orange zones in a pink stone)
1. Merging orange in pink
2. Orange with pink zones
3. Merging pink in orange
4. Pink with orange zones
In Asia the "Orange Pink" (1.) is the most valued variety of the four. In Europe it seems "Pinkish Orange" is favoured.
Because of their value Padparadschas have always been the object of heavy treatments. Not only heating but complete "re-coloring" is common. Treated padparadschas are however of little lasting value. Diffusion treated Padparadschas for example are about as a rare and valuable as traffic jams in Colombo.
Any good looking natural Padparadscha that does not cost significant money is a fake (no exceptions).
When buying true Pads on the web, make sure that the stone is graded as "pinkish orange" or "orange pink" by an independent lab.
Blue sapphire is in fact the number one in sales of all colored gemstones. Famous are Cornflower, Velvet- and Sky-blue and the rare Kashmir blue. The roots of the latter color lie, of course, in the origin Kashmir. However, since the mines there have run dry the term 'Kashmir' is commonly used for a specifically sleepy and hypnotic type of deep blue (like the 3ct natural Burmese sapphire above).
Blues are routinely ultra-high heated to create this darker kashmir-like shades. Sri Lanka exports containers of an ugly whitish stone ("geuda") which turns into blue sapphire under ultra-high heat. An estimated 95% of all Sri Lanka sapphire is treated. Untreated natural blue Ceylons are a rarity.
Natural Blue sapphire on photo: The chameleon
Anybody who has tried to capture unheated blue sapphire on photo will have realized that it is extremely sensitive to the light source. Far from understanding the color perception of the human eye versus that of a camera, we can only note that blue sapphire is a camera-chameleon.
The slightest change in angle, distance to, or the light itself result in tremendous changes of the captured color. The photos below show the same 3.5 carat blue sapphire without any further editing (other than sizing).
Photos above: Blue sapphire can be photographed "into" many hues.
Depending on the light source and angle the camera transmits different hues and shades. Hence, a "sell & run" trader could offer this stone as cornflower blue, purplish blue or even as a light Kashmir blue - resulting in very different prices.
Yet, the "real" color, meaning the one which the eye perceives, could be described as 'deep steel blue', and is best shown in the last photo (#3 in 2nd row).
However, deviation between reality and the photo are not always the result of bad intention or fraud. Especially light colored sky-, marine-, and steel-blue stones are in fact difficult to capture correctly. Therefore any photo should be accompanied by a straightforward grading and a written description taking up any issue that the photo might withhold from the buyer.
The lesson to learn: When buying natural blue sapphire on the web, always carefully read and consider the seller's description and grading. When the "real" blue might be hard to capture, it is worthwhile to pay attention to all other information the seller gives. (Hence, if we say that a stone is lighter colored or more steel than sky blue, we mean it.)
Photos above: Three untreated yellow sapphires suffering heavily in front of the camera, though, in fact they only have minor, hardly visible inclusions.
A natural yellow sapphire free of inclusions on the other hand is a grateful gem to work with. They will shine and sparkle especially when exposed to a little bit of sunlight.
Frequently however their luster is so strong that the camera captures them just as a blurred light source. In this case the photographer has the choice to either show the stone as a somewhat fuzzy shining star, or he has to sacrifice the luster and show the stone from the side only. We usually prefer the shining stars:
Photos above: Three natural yellow sapphires shining beyond the camera's capabilities.
Frequently we also experience that the greenish character of a stone becomes strongly exaggerated by the camera. Some stones in fact turn so green that they are hardly recognizable as yellows anymore. This presents one of the rare cases in which it might be legitimate to manually decrease the amount of green captured by the lens.
Photos above: Natural lemon yellow sapphire that showed mostly green through the camera. Only after reducing the green digitally did the real color prevail.
Again, the primary goal of any selling photo is to present the stone as close to reality as possible, yet the additional description ought to mention any potential deviation between photo and eye perception.
Some cultures and languages use the term "purple" differently. As most North Americans and Europeans, we take purple as a color on its own. Violet, also a mixture of blue and red, lies closer to the blue and is therefore counted into the blue gemstones.
Unheated purple sapphires are far undervalued given the strong color sensation they offer. A good natural purple is as thrilling to the eye as a good blue or violet. Nevertheless they have not been getting much attention until the quest for untreated ruby made many people consider other colors than the classical pink and red.
Yet, besides the terrific but rare electric purple, collectors seem to prefer stones with an undertone rather than fully saturated purple ones. This looks like an exception to the rule "the higher the saturation the higher the price".
A reason for this exception may be found in the way pure purple defies the camera.
Purple sapphire on photo: Poor in Solitude
When looking at images of natural purple sapphire on the web one quickly realizes that they can not compete with the dazzling presentation of good blue, ruby or pink.
Whenever you see a breathtaking image of a purple sapphire it is mostly the secondary hue that gives it the "bang". Pinkish purple, reddish purple or violet/bluish purple are great models, but purple on its own does not perform well in front of the camera.
The following sapphires are fine gems for the eye, yet the image does not transfer them equally well. They are examples of rather "pure" purple in different tones:
Photos above: Fully saturated purple shows somewhat dull or lifeless in front of the camera. Add a tint of secondary color, and that changes dramatically.
The following three stones, all with strong color cross-over, do very well in front of the camera. They immediately catch the eyes attention and leave no doubt about their attractiveness.
Photos above: Purple as/with secondary hue is very photogenic. Of course, these stones are in deed fabulously intense colored but they also show it straight away.
Thus, when buying purple sapphires on the web: Give them some credit!
You might well be surprised how reasonably you have obtained a fully colored untreated sapphire.
Though prices shall not be a function of the photogenic capabilities of a variety, they do influence the market situation. Hence, purples are sold relatively more expensive in the traditional channels than they are sold on the web. This is true for all gems, but especially for the camera-shy purple.
Pink, being a lightly colored form of red sapphire or ruby, has become popular in recent years.
Its colors range from a light lavender rose to the so-called "hot pink", which resembles a vivid bubble-gum hue.
Aside from padparadscha, which is partly orange, natural pink sapphires have become the most expensive variety within the fancies.
Prices of pinks vary greatly with size and color intensity. However, untreated hot pinks of several carats have buyers lined up at the mines. In the wake of this popularity prices of pink spinel have increased as well.
The fact that heart shapes are much more frequent in pink sapphires than in any other color points to the emotional occasions they like to be used for. Especially Japanese buyers love big pink hearts.
Hot pink was once a unique offer from Sri Lanka, but we do not see that continued. Madagascar has taken a dominant position for pinks, but most stones are heat treated and are not clean.
(Remark: Though Madagascan stones are sometimes heated at lower temperatures (600°C), we feel that "treatment is treatment". To distinguish between low and high temperature heating does not help at all, but further complicates the situation for the buyer and increase the confusion in the market. Either a stone has been artificially pampered with, or not. If there was no change, then why was it heated in the first place? "A little pregnant does not count.")
If you want a truly natural pink you will have to search longer and, no doubt, pay more.
Pink on photo: Well, that depends.
Ranging from the most tender-baby-complexion to alarm-button-shocker-hue, natural pink does not allow a simple evaluation.
Light pinks are notoriously difficult to capture. Like yellow they suffer from exaggerated display of inclusions, re-pay good luster with fuzzy images and pretend to have windows where the eye sees none. In fact light pinks are known to have made photographers quit their jobs (or being fired).
Below are three adorable pink sapphires that will stop your breath in person, but they are hard to capture digitally in an attractive manner.
Far from cheap untreated light pinks don't forgive shallow areas, over represent inclusions and either swallow their luster, or turn out fuzzy.
Photos above: Light pinks are mercilessly self-critical.
Strongly colored pinks on the other hand are more than robust. The following shots were immediate photographic "bull-eyes", and do neither exaggerate the stones beauty nor understate their weaknesses. Further around the color wheel this is taken to the extreme when even opaque rubies still make relatively good photos.
Photos above: Hot pinks jump straight into the camera without problems.
As a rule, the more color in a pink the more critical you should be about any flaw you can see on the image. Be wary with hot pinks that look too included or windowed, they probably are. Unless the price reflects the visible flaw and the seller names it for what is it, you might have a bad awakening.
On the other side you can make a good catch if you find a fine, but lightly colored, pink that is undervalued due to its bad photo manners.
Truly colorless sapphires are called "white", and are said to be found exclusively in Sri Lanka.
Fine untreated white sapphires have become rare since they can be turned blue, orange or yellow with high heat, irradiation and various other treatments.
White sapphire rivals diamond in some ways. Thus they were often used as a substitute. However, many people have become aware that they do have their own charm, and since then they are valued far above mere cheap wanna-be diamonds.
Most white sapphires like the pinks, are heated, even if on lower temperatures. Some like to conceal this as "only blow-heat". We don't.
Many whites do have light hues - pink, purple or a tint of blue. The border between a pale blue and a white sapphire with a blue tint is not clearly set. From the point of untreated stones, we define the border in favor of color.
A white sapphire that shows some, say, blue but may not be called a blue sapphire, is here referred to as a "tinted white". Such a tint may be imagined as the lightest of all tones. Clear water in a glass bottle for example or ice leaves an impression of being bluish, or white marble might shine yellowish. However, one wouldn't call this blue or yellow straight away.
The tints in white are in fact often so fine that professional graders can not agree on them. Some labs define such a stone as "faint blue" some tend to call it "colorless". At the end of the day it comes down to your personal perception and taste. In any case we will explicitly mention the faintest idea of color in our comment.
All whites do exhibit color when in colored light of course, but that does not count as a tint.
White sapphire on photo: Capturing the stars.
Here are some examples of sapphires that show various tints, but may still be counted as whites:
Photos above: Three unheated white sapphires with just an idea of color. The pinkish center stone is the same as above. One photo was taken with some sunlight, the other one in very cold dim day light.
When choosing a tinted white sapphire on the web, make sure that the stone does not only show colors resulting from an external light effect. Ask the seller and see for the color definition of the lab certificate if you are not sure.
If there is a tint, and you like it, you might have the chance for a bargain in your color of choice.
At any rate, white sapphires are thankful photogenic models. They sparkle and shine with all might. Surprisingly they are not as sensitive to inclusions as one would expect from the experience with yellow or light pink.
The only difficulty one encounters with whites is to rightly capture their luster. Some well cut whites are so good in throwing back light (which is somehow the life-purpose of any gem) that they can't be photographed from the front. Those stones you will find to be shot from a side angle.
Though not satisfying this is often the only way of capturing the stone without simply having a fuzzy light in, say, oval shape on the picture.
Here are some whites that had to be photographed from the side because their luster was too strong to be captured.
Photos above: Three whites with luster too strong for the camera. Hence they had to be shot from the side.
That of course does not mean every white with a frontal photograph are dull.
The following stones sure do have extra fine luster but they probably dispense the light in a way that does not blind the camera, and/or have been shot in slightly dimmed day light, and thus are less aggressive.
Photos above: Whites allowing frontal shots in dim light.
As so often in gem photography, one can not show all qualities (or flaws) in one shot. If the value of the stone (and thus the invested time) does justify multiple views, a row of photos is probably the best way to overcome this issue.
However, there is an obvious connection between an in-depth multi-angle multi-light photo-analysis and the price of a gem. Thus we do not generally photograph every stone from every angle in all light conditions, but deliver additional photos on request.
At any rate, a seller should be willing to provide you with a written statement or an additional photo if you have doubts about certain feature like color or are worried about a flaw.
A last advice regarding untreated white sapphire: Buy them before prices go up.
Compared with other green gemstones (say tsavorite or tourmaline) the green variety of sapphire makes honest but simple photos. Compared to other sapphire colors like pink or blue, they are, well, not-so-shocking.
There is no neon-electric or extraterrestrial chrome green in sapphire. Theirs, with iron as color agent, is an earthy topic. Even the most painless photo-shoppers on Ebay do not dare to display them in shock-green. Green sapphires are pretty much what-you-see-is-what-you-get.
Green sapphire does come in certain types from certain origins. There are exceptions and the usual oddities but one might say that there are three classes of green sapphires.
Here are two classical green sapphire from Australia. Their lush greens are rarely mixed with blue. When buying untreated Australian green sapphire keep away from too dark stones. Check for the light settings on the pictures: It should not seem artificially over-lit or brightened. Australian greens are still a great bargain.
Then we have the more floristic greens coming from Sri Lanka; and her geological neighbors in east Africa. Typically underplayed with yellow or brown they range from brownish olive to the most tender sprout green with frequent blue-greens thrown in.
Watch out for the blue-green like the one here, they have gained much financial ground over the last years. Especially those rare specimens holding equilibrium of green and blue have been strongly appreciated. Bargain hunters may still find such stone priced at greenish levels.
Finally there are are the legendary US sapphires from Montana with bright metallic often bluish watery greens. With mostly light tones they are a difficult bunch on photo, but very rewarding in person. More often than not, they display cross-overs between blue and green; and they also have great luster which is desired but difficult for images:
Aren't they truly different in character?
They do not compare with the posh blue, green or pinks of the world. Austere, frugal and often pale; they have an arctic charm and it shows on photo.
Commonly stars are known in ruby and sapphire but they also appear in garnet, spinel and other less known varieties. There are differences between those stars but we will here pretend that nature made all stars equal.
Gemstone phenomena, especially asterism, are a tough call to judge on photo. However, no normal jeweler will be able to show you a fine natural star sapphire, let alone a selection to choose from. Good stars are rare even beyond the normal gemstone rarity. Unless you live in a metropolis or travel to Tucson or Basel, the internet is the only place to compare and buy such a gem.
Looking at images on the web, stars seem to be quite an ugly bunch. Rarely do they show nice colors, often they are zoned, patchy, heavily included, silky, egg-shaped and at times the asterism is hardly visible at all.
And of course you will find many "perfect", "fully colored", giant star sapphires or rubies for a few dollars. These are synthetic or surface diffused or lead-glass filled gems which are mostly worth just as much as they cost.
There is nothing wrong with twenty carat Linde star for fifty dollar, but be wary of those sellers trying to offer them as real.
Here are some typical examples of undisclosed fake stars:
So, they are either ugly or faked?
No, don't be discouraged. Real, natural stars are mind-shaking and heart-breaking.
Many star skeptics have become sworn star fans after their first encounter with fine quality:
Ceylon Star Sapphire
Mogok Star Ruby
12 Ray Burmese Star
Here is what to look for when selecting a star sapphire or ruby online.
The value of any star gem depends strongly on the quality of its asterism, which is defined by (no order):
Symmetry & linearity
Completeness (6 rays mostly)
Travel (smoothness of movement)
Lucidity & Depth
The relative importance of these criteria are questions of personal taste, culture and fashion. Most collectors would perhaps trade in some off-centeredness for good movement, or overlook a meandering leg while frowning at a missing one.
We feel lucidity, travel, position and completeness may be most important and price relevant.
Only then, with decreasing relevance, come:
Finish (top and bottom)
Asterism and color together easily make up 80% of the value of a star (sapphire, ruby or any other variety).
With ten dimensions (as compared to the old 4 Cs) stars are a quite demanding topic. But they are rewarding, too.
Let us tackle each issue separately from the web's point of view:
1. Sharpness is easily shown on the web. Here are three stars (spinel and sapphire) with decreasing sharpness:
Three remarks, though:
There is an ideal distance between spotlight and the gem bringing out the sharpest star. You may assume that the photo captures this point. (unless stated otherwise in the grading report)
In general, a camera shows stars not as sharp as the eye perceives them. Hence, when you see a sharp star on photo you can safely conclude that the star is actually very good in person. If you can just make out the star on the photo, it will be fleeting and in need of a strong single spotlight.
Please be advised that one may well find faked (photo-shoped) sharp stars on Ebay or elsewhere. As always, if it is too good to be true... and never buy without 3rd party certificate.
2. Symmetryand linearity too, are easy: What you see is what you get.
Photo: A rather symmetric white star sapphire with some snaky rays.
3. Completeness: No problem either. Count the legs. If the gem on the photo misses one leg it is likely missing for real (unless the grading says otherwise.)
Photo: Star Sapphire with two missing legs
4. Travel, the ability and smoothness of the star traveling over the stone, is not really possible to show on the web (not yet at least). Until online video technology has advanced further, you will have to rely on the seller's description and check later in person.
Ideally the star follows a light source smoothly, not jerking and jumping, while staying intact and sharp. Don't expect perfection though: Every star has a weak area or two. Value reducing would be a loss of completeness or even a sudden disappearance of the star during movement.
6. Position too, is a tricky business on the internet. In order to show the star on a photo one must bring it close to the center. Thus, on a photo, the star will usually be centered. But that does not mean it actually is.
Photo: Three stars looking halfway centered which are in person off centered:
Even a 100% centered star would need camera and spotlight in the same position (which is next to impossible). Hence, position is always a criterion that one must question further even if the photo looks great.
Sometimes you may see the light coming obviously from the side while the star sits centered, meaning that, when the light is moved up, the star will probably shift off-center. However, this is not 100% conclusive. Mostly you will need to rely on the seller's evaluation.
Whenever useful we try to put a number to off-centeredness: "45 degree off-center" for example indicates that when the spotlight is positioned straight above, the center of the star sits half way down the stone. Ten degree would mean the star is just slightly off center and more than 60 degree would send it nearly over the edge.
6. Lucidity & Depth are connected. In one extreme we will have completely opaque material with the star sitting on the surface. Opaqueness is easy to spot on photos. It looks like a solid piece of material with the rays fixed or painted onto the surface.
Photo: Opaque star ruby with the star confined to the surface.
At the other end of the spectrum we may have highly transparent quality with the rays reaching into the body. One can, however, not expect 100% transparency because needles are necessary to break the light and show the star.
If the needles are very fine and yet the star is clearly visible, then ... There is magic: The rays sway like silver curtains inside this most dense material.
Photo: Semi-Translucent star sapphire with rays reaching into the gem
Most stars however are rather opaque characters and transparency is highly priced.
So much to the evaluation of asterism.
The remaining four points are also relevant in normal gems but some additions are helpful.
7. Color: Strong colors are extremely rare in stars. Even the best star will have a silky, silvery sheen to it which clouds its saturation. This is unavoidable. A star needs needles.
Most stars come in grayish, foggy mild colors. Exceptions, like the one below, exist but they are very costly and yet can not rival the intenseness of a 100% transparent gem:
Novices will be disappointed when expecting to find a neon red ruby or a hot pink sapphire with perfect asterism.
One has to appreciate the silkiness as part of the phenomena, and see the color as an add-on. Even grayish white stars have good value if their asterism is of high quality.
The main problem, however, when judging colors on photo springs from the fact that any spotlight, needed to show the star, affects the character of the color. There is no cure to this.
If the spotlight alters the color too much we often add a "no-star" image to show the gem's "2nd" color. This means one image to show the star, and one more to show the color (without a spotlight) under mixed and diffused light conditions:
However, this is not fully satisfying since star quality and color saturation interact. Again you have to read the sellers description carefully and trust his judgment until you can examine the stone yourself.
There is a trade-off between a weak star and a full color: The finer the needles, the better the color potential, but the weaker the star.
Hence, the worst of all possible stars will be valued close to a cabochon of similar quality. Thinking of ruby, we would, at some point, discard the asterism and cut the cabochon into a facetted gem with that sought-after silky ruby sheen.
8. Clarity: Stars are by nature often more included than normal facetted gemstones (beyond their needle structure). This may be connected to their geological origin as semi-transparent material. However, inclusions should not dominate the overall appearance or hinder the rays from traveling.
Photo: Star padparadscha with orange inclusions and yellow color zones adding beautifully to the sunset theme.
Stars also often display stronger color zones. Here too, one has to be tolerant. As long as the star runs unhindered through those color zones you are still on the good side, even if the price of such a gem must be well below an evenly saturated sample.
9. The shape of a star is limited to round or oval cabochon with rare exceptions.
Photo: Pear shape star sapphire (pair)
Generally, asymmetric shapes or other unevenness will reduce prices or should be re-cut straight away. Stars may come flat or dome shaped but this isn't of much importance since there are no windows or blackouts to fear as in facetted gems.
10. Finally the finish of a star: While the dome must be smooth and evenly polished the bottom is often left rough and uneven, frequently even with unattractive edges, holes and other flaws. Don't worry about it.
Photo: As-good-as-it-gets back of a star sapphire: Unpolished, no over-weight, no flaws.
The only thing that counts in a star sapphire or ruby is the top. Of course, in an ideal world, the bottom too can be pretty but don't count on it.
The bottom does not need to be nice but must be as small as possible, not bulging and thus producing extra weight. Enough bottom to accommodate a setting is all weight you want to pay for. A tiny star sitting on a giant rock of corundum will not be priced per carat.
The most important quality of a star sapphire, ruby (or any other variety) is its asterism
The main criterion of asterism may be lucidity, completeness, position and travel
Lucidity and completeness are possible to judge online
Position and travel are not conclusive by photo only, but need the sellers input
Asterism and color together determine the value of a star gem
Strong colors in transparent stones are highly priced but extremely rare
Some fogginess/silkiness is necessary in every star
Colors may vary depending on the type and intensity of the spotlight
Watch out for over-weight bottoms
Treatment of Star Sapphire & Ruby:
Many gem dealers will claim that stars can not be treated. This is nonsense. They can not be ultra-high-heated above 1200 degree because this might melt the needles. Stars are regularly heated below 1200 degree, lead-glass-healed, diffused or filled with bismuth or other chemicals.
In a more thorough approach let us follow the 4C to evaluate a pair:
Carat (size): Many people get overly focused on searching identical carat weight in pairs. This is not necessary and indeed very rare to find. More relevant is the so called "face", the upside dimension of a gem. Two gems might have the same carat weight and yet very different faces and vice versa.
As a rule of thumb you should be searching for gems in the same weight class, say 2-3 carat and then, more importantly, look at the dimensions of the face. Consider width and length. They are most important since they determine the visible face. A pair with too much deviation in the visible part is no good for jewelry.
How much deviation is too much? This is better looked at in relative, rather than in absolute terms. One millimeter difference on a 20mm pear shape might be acceptable but a catastrophe on a 4mm round gem. Barring exceptions we allow pairs to have max. 5% deviation from each other.
The third dimension, depth, is less relevant for your choice assuming that the face is similar and that there are no bad windows. Depth however is the main parameter for weight. Hence, you may find gemstone pairs with equal face dimensions but very different carat weight. Yet, they can be perfect twins for jewelry if the cut is good enough to cover up missing depth, which leads us to the next point:
Cut: Choosing two different cuts or even shapes, say a trillion and a square in a pair is quite exotic; and it is done rarely (but can be charming).
Generally, however, people want near identical cuts. Ideally a pair has been cut to match. It was thus faceted by the same cutter from the same rough material. With "same mine run & same cutter" one has a good chance of getting two gems with a similar character to begin with.
The more important luster is for a gemstone, the more emphasis will rest on identical cuts. A pair of white diamonds for example needs to be machine cut to be 100% equal (which they mostly are in calibrated sizes). In a less lustrous gem, say a midnight blue sapphire or a brown tourmaline, the details of each facet will not be so influential.
As mentioned before, differences in depth can be covered by a clever cutter but this has limits. Too little depth results in windows and there is no way out. If both gems show similar windows that might be OK, but it is very disharmonic to have one fish-eye and one full body sparkler displayed together.
Color: As always in this trade color beats them all. Ruby, tsavorite or sapphires are primarily bought for their magnificent colors and only secondarily for their luster. Some gems like Mali garnet, titanite or demantoid come with fire and color. As pairs they shall be judged by cut and color in equal parts too.
However, most gems are color-first animals.
Tone: Differences in tone are easier to stomach than differences in color composition (mix of 1st, 2nd and 3rd color). This is true especially in darker varieties. (Remember: Tone is the amount of black/white not the saturation). A deep blue sapphire of medium dark 75 will easily fit with a medium dark 80. But be careful with e.g. light yellow or green. There, even small differences in tone will be very visible.
Remark: We would rather suggest using pairs of completely different colors for jewelry than allow different hues in one color. Using two unconnected colors however is quite exotic and we do it only on request. (How about a neon red spinel set with two chrome green tourmalines for example?)
Hue: Where color is king - in pairs it is double. A pair with different color composition will hardly make a nice pair. Add only a bit of purple to a ruby or a tint of violet to a blue sapphire and you will need many meters (not only a face) to separate them from a red-red ruby or sky blue sapphire. A greenish blue and a bluish green sapphire, or a rose red and an orange red ruby, can not be called a pair at all. As soon as the color is visibly different there is no pair.
Remark: Hence, matching pairs are even rarer in natural gems because they lack the uniformity of treatment. Heat or diffusion brings out similar colors in similar rough. The result is a more consistent color mix. Matched unheated ruby or sapphires are therefore a difficult hunt. In fact, this is one reason for the spread of treated gems: Making a necklace with 50 matching sapphires is only possible on a high budget or with high heat. Similarly the industrial production of 5,000 rings with a similar colored blue gem demands controlled artificial coloring.
Clarity: A matching pair should be on the same clarity level. One may accept a "free of inclusions" next to a "very slightly included", meaning both are clean to the eye, but anything that is visible in jewelry should at least be visible in both gems. If a pair comes from the same mine-run, one can actually find beauty in combining identical types of visible inclusions: individual, charming and easy on the budget (think rutilated topaz in a pair).
Width and length determine the visual similarity of a pair not the weight
Better two windows than one
The more important luster is, the more important are identical cuts
Same-mine-same-cutter pairs are best to start with
Differences in tone are sometimes tolerable but differences in saturation are no-no
If inclusions are tolerated they must be visible in both stones
We avoid the term "pigeon blood" because its abuse has rendered it meaningless.
Rule 1: Insist on at least one image with light in the back.
Mild colored ruby will easily hide inclusions from the camera. Make sure the image does not only focus on the surface of the stone. A mild ruby needs an image with light falling in from the back of the gem. This will show you inclusions with all honesty.
Pictures: Mild colored rubies in front of daylight
Many images on the web are "front-loaded". They show only the surface of the gem but not the inside. This is done to peddle translucent, or even opaque, cabochon quality as facet grade ruby.
Rule 2: Mild colored ruby needs clarity.
Heavily included ruby in mild colors looks dull in person. The value of such cabochon quality corundum is negligible in comparison to transparent ruby (unless it displays a star ruby of course).
The scarcity of good material has somewhat lowered the bar to what is labeled as facet-quality ruby. A translucent or opaque mild ruby might look OK on the photo, but the stone will be boring in person and have zero luster. No good.
Ruby is by nature more included than, say, tourmaline. You will only get a "free of inclusion" if you have very deep pockets. However, some inclusions are wanted, while others are to be avoided.
Picture: Burmese Ruby with rare "Free of Inclusions"
Finest silky needle structures are delightful, shattering light rays into a hypnotic gleam. Thicker needles are interesting under the lens and do little harm to beauty.
Less attractive, and hence price reducing, are whitish clouds, visible black spots, growth lines with weak color zones or broken crystals.
Rule 3:See inclusions but imagine glow and luster.
While mild ruby will swallow its inclusions, it will also hide its luster and no high-end camera can change that. However, even the worst cut ruby has luster as long as it is clean. Unfortunately, it is often impossible to capture this on photo.
Hence, in mild ruby photos, you need to be picky with inclusions but may be generous with luster and radiance.
A pleasant mild ruby will never disappoint as long as it is clean.
Picture: A strong color can make up for a "Moderately Included"
For wild rubies inclusions are only a secondary concern. Color is king. A neon ruby can easily be moderately included without looking dull. Even in translucent material a neon red is still very attractive and many budgets will be limited to more or less included material. Translucent rubies are OK as long as the color is extra terrific and the price right.
Rule 3: A fine wild ruby never holds still on an image.
Something always seems to be moving in them. Often it looks as if a flickering fire or a hot swirling fluid is caught in the gem. As if there is something alive in them - now, if that is not wild!
Pictures: Best rubies have "inner life" and split purpel/violet from red
Rule 4: Beware of digital enhancement
Since color is half the rent, some are tempted to "improve" their pictures for the web. Avoid "super bargains", plastic-like hues, and check the photos background: It shall be neutral and real (the gem should not be "cut-and-pasted" into a new background). Light conditions shall be normal (mixed light, filtered sunlight). Tungsten light alone is not enough. Ask for images in different light settings and angles. One can't easily repeat a faked or stolen photo in variations.
Pictures: Common digital tricks in ruby images
"Front-loaded" image hides inclusions; Pinkish background indicates digital color enhancement
Extreme (artificial) hue for $199/carat too good to be true
Titanites are not as tough as diamond or sapphire hence they can't be worn while free-climbing. However, there is zero risk of scratching them in earrings at a dinner party (not unless your date is Hannibal Lecter).
We have set quite a few Titanites in protective rings and pendants and they all stand their ground in daily use:
Titanite on photo:
Sparkle can not be transferred on a photo, it needs movement. When you shop for Titanite (or any sparkling gemstone) the quality of the cut is most important. Diamond cuts (invented to work with high dispersion) are the best in Titanite too. Avoid windows and cuts with too few facets.
Though they do display many colors Titanites may have different characters. These may range from an earthy green or hay yellow to a lively red ocher and many other combinations. This is sometimes hard to transfer on photo, so pay attention to the seller's description. If our grading reads "orange/green/red/yellow" then orange is the most dominant colors followed by green, red and so on.
Given their affordability and the spectacle they offer, Titanites are a simply terrific deal.
Unfortunately our contact to the Pakistani mine (build up in the relative calm of 2007) has defaulted so we are not able to predict future availability or prices at this time (07/08).
Spinels come in a vast variety of colors, but are not as confusing as the garnet family. The most famous colors in spinel are blue and red, but one will find fine purple, violet, pink, mauve, greenish, or black spinel. They also come with stars and color changes but have not yet gained much attention. What dignifies all spinel is their excellent luster and durability for jewelry.
The king amongst blue spinel is a rare variety colored not by iron but by cobalt. This cobalt spinel is found only occasionally in Sri Lanka (and elsewhere).
In the red hues, ruby-like colored spinel has sky rocketed in price and popularity, directly followed by hot pink and padparadscha colors.
It appears that in recent years spinel has made it from a sometimes hardly distinguishable, sapphire-substitute to a variety standing on its own. Thus they do not come cheap anymore. Even our remotest miners have started to distinguish spinel as better than other 'non-sapphire-gems' and thus have started to ask much higher prices. However, they are still a comparatively reasonable alternative to ruby or blue sapphire. The less known varieties of spinel (purple, mauve, etc.) offer not only superb visual experiences but are most likely also a good investments in the long run.
Spinel on photo: As one can see above: No problem! Like sapphire spinel are quite photogenic. They do not deceive in color or luster and are a grateful object for exquisite images. As all gems they are sensitive with inclusions in the lighter tones only.
A Danburite that looks good on an un-doctored photo is probably a beauty in person. If you have a good eye you may make a snatch with a photo-shy Danburite that will be much nicer in person.
This said, Danburite has a relatively low refractive index and will not easily sparkle as much as you would wish in a colorless gem. Optimized for brilliancy they will shine but not disperse light as diamond or, to some extend, white sapphire do.
With not much color and little luster to show, Danburites rely on good cutting. Big and clean Danburites from South-America have been a recent boon for precision cutters worldwide.
So far we have not heard of any treatment in Danburite. If they come treated they will probably be diffused into some unnaturally intense color and easy to spot.
Green grossular garnets (of which Tsavorite is the more famous) truly are a "new" gem since their discovery has been quite recently. Tsavorite are the most expensive garnets in the market (besides demantoid perhaps).
They are found mostly in small sizes. A three carat Tsavorite is considered a giant. Most found are below one carat but even the smallest Tsavorite is far from humble.
The very best are shocking green and size doesn't matter. They are like a volcano of extraterrestrial color, and if you want a modest gemstone green garnets are probably not right for you.
They do have good luster too, but color is most important. Like in emerald, inclusions are no killer-criteria as long as the color is not affected. Hence a colorless inclusion may be tolerable but we wouldn't want brown zircon crystals.
Tsavorite on photo: Difficult, to say the least.
They tend to look darker than they actually are, and often black-out. This may be a result of their unique dense hue. It is possible to throw so much photo-technology and light at them that they loose all blackout but then they also loose their individual character and start too look all alike.
This said one might distinguish between an intense metallic green and a more alarm-color "venomous" green. The latter being a more earthy color one might expect in a poisonous coral fish and the former being without parallel in nature.
Given their availability in small sizes and their intense color Tsavorite are ideal for small but visible studs or as side-stones to contrast an intense center stone.
Pyrope is typically described as blood or wine-red, while his name refers to the Greek word for "fire". Though pyrope does not have what one calls "fire" in a diamond it is definitely as red as it gets. How red is that? In case you are familiar with Spanish wine you might have a look at a Senior de Los Lamos '67, which will cost you much more than buying a pyrope, but tastes better (pyrope does not). You might also take blood samples from your neighbor's ox, but that too might not be a particular wise course. It is said that once upon a time pyrope has been more popular and much higher priced. Today pyrope is, behind the almandine, the best deal if one wants a red-red gem of significant size without selling his family.
Pyrope on photo: Pyrope typically shows blackish areas and little luster on photos. Their color gets across well, but they usually tend to show more orange or brown than they actually have. Darker pyropes simply refuse to be photographed yet look good in person. They are a fine color-bargain to hunt for.
Hessonite is always clearly distinguishable: See a hessonite through a lens and he will appear to be melting inside, while you can not see anything special without the lens. Melting?
Some gemologists call it a "treacly" or 'swirly' appearance, which comes from inclusions that actually look like a petrified fluid. Hessonite is a wonderful stone in all yellow-orange to brown-red hues. Though not in line with the standard scientific gemology literature, I find hessonite in all red garnet colors from a fiery orange to a simply traffic light red. In any event they make exquisite colored gemstones and are a true miracle when seen under the lens.
Hessonite on photo: Though hessonite is wonderful to look at they struggle with serious problems in front of the camera. Unfortunately 'treacly' transfers on a photo to 'fuzzy'. One needs to experience a hessonite live to be able to capture the information hidden in a photo. As a rule, concentrate on the color and blend out the fuzziness of the photo. If you like the color you will have to test the luster in person.
Almandine is the most famous garnet variety in Sri Lanka. They seem close to pyrope but are of a more intense red mingled with pink and/or violet. Though often included with a very fine needle structure (which is a pleasure to see under the lens) they do have all fire and luster one might desire. In fact, a good almandine can be so amazing under a spotlight that you will not want to take your eyes off that sparkle again. Almandine is more expensive than pyrope but a still a fine deal compared to the price of a similar color thrill in e.g. spinel or ruby.
Almandine on photo: The needle structure in almandine tends to look a bit fizzy on photos. Nevertheless almandines are a pleasure to shot - they glimmer and sparkle in fine red tones and transfer well on images. Like pyrope, almandine color usually does not vary much between with day or tungsten light. Also like pyrope they tend to show black-out areas which are not as dark as they seem in reality.
Rhodolite and raspberry are red garnet with strong pink and/or purple hue. Both are characterized by their color and one will find different definitions over time and literature. However, if almandine and pyrope are wine & blood, raspberry and rhodolite are berry & flowers. They are the best deal in town for progressive color adventures. Both have excellent luster and a "juicy" color play that often mocks any description in plain words. Truly appetizing colors: Grading them sometimes makes me want to rush to the market to see whether I can find some berries.
Rhodolite and raspberry on photos: Both stones can be miraculous and nerve-wrecking in front of the camera. They are the chameleons amongst gemstones. We have seen furious discussions between photographer and grader about what is the "real" color.
Truth seems to be that there is no truth. But that doesn't matter much because these stones always excel their photos. Other than e.g. with sapphire one can not make a photo too good when in comes to a raspberry and rhodolite.
Color changing garnets are an exquisite rarity (and I mean rarity) in Sri Lanka. In absence of any gemologist most traders and miners in Sri Lanka consider (or wishfully think) any color change garnet to be an alexandrite and thus have dollar signs in their eyes when they get their hands on one. Therefore most color changing garnets start their life as alexandrites, but somewhere down the supply chain somebody has a bad awakening with them. On the other side, one must ask why shall a beautifully changing garnet have only 10% of the value of a dully changing pale alexandrite? That of course is a complex question of market mechanism. If one simply admires the magic of color change he might forget alex (and sapphire) and hunt the last color change garnets before the deposits are depleted.
CC on Photo: Catching color change on photos is one of the trickiest tasks in gemstone photography. This counts not only for garnet, but also for all color changers. It is so tricky, that I can only warn of too good looking but cheap color changers. A color change that is fully visible on photo without photoshoptricks is truly rare and will never be cheap (at least not in natural stones). Buying two carat 100% color changer on EBay for two dollar is like ordering a Maybach for the price of a bicycle. No complaints about dishonest sellers please!
Zircon has suffered much bad PR due to synthetic stones with the trade name "Cubic Zirconia". In addition to this the use of zircon as a cheap diamond rip-off has led many people to believe that zircon is synthetic or some kind of fake.
It is not! Zircon is a wonderful gemstone variety that has much more to offer than all the treated zircon in uniformed colors roaming the jewelry market.
Zircon is the most brilliant of all colored gemstone (only thus he was misused as an imitation for diamonds). His brilliance and luster is unbeatable and his high birefringence is most unique. Naturally colored zircon can be green, yellow, brown, (rarely) blue, (very rarely) red and often colorless. In any color he shows a stunning fire and magnificent luster. Mostly very clean and found in good sizes zircon is a yet little known opportunity for novice collectors and experimental jewelry makers. They offer adorable colors and excellent luster for every budget. A light yellow zircon is nearly as fascinating as a fancy diamond. Sri Lanka has for centuries been the best source of gem quality zircons.
Zircon on photo: As a rule, zircons are even better than their images. The birefringence of zircon is so dominant that he is difficult to photograph clearly. Additionally they are often so brilliant that they seem to simply mirror light on the image. The strong luster of zircon is rather hindering for the color show and when it comes to zircons, one shall rather trust the seller than the photo.
(This can be said as a general rule: Don't buy gems based on photos but on the reputation of the seller and based on the security of his return policy. It is not a pleasant shopping experience if you buy a bad stone with a super photo that can't be returned.)
Unfortunately, we do not get many aquamarines in Sri Lanka (at least not fromSri Lanka). Those we get are of light colors (untreated of course) with a greenish blue hue. The most expensive color in Sri Lanka is a sky blue. In former times the most wanted color was actually (in line with the name) the greenish blue. However today the sky blue is higher priced. Even more than amongst sapphires, aquamarines are generally heated to get stronger blue. If you have decided to stay with natural gemstones look out for light colors. I personally think the greenish blue ones are very beautiful and make real unique stones.
Aquamarine on photo: Light colored stones are notoriously difficult to capture. Especially in stones of good luster the light thrown back out of the stones tends to override the stone's color. Hence even if an aquamarine has a solid clearly visible blue hue he might in the photo show to be nearly colorless. Light colors also take inclusions much more serious on the photo than in reality. Again, trust the seller not the photo.
Amethyst is very popular purple-violet quartz. It is available in fine colors and good sizes but does not demand high prices. A lot of amethyst is burned into citrine but the original stone is much more attractive. In fact, seen in color/price relation amethyst might compete with garnets. The deep purple cross-over to violet is just delicious. Amethyst is probably the only gemstone variety one can collect buying only the best "excellent" stones on a moderate price.
Amethyst on photo: No problem. Amethyst is grateful in front of the camera and makes easy realistic shots.
Tourmaline is the most versatile gemstone family. Not only do they show themselves in all colors from brown to pink, but they are also famous for bi- tri- and multicolored varieties, and rare color changers. In Sri Lanka we rarely find pink, blue and red tourmaline but are blessed with green, yellow and brown in all mixes and variation. For those who dislike today's flashy fancy colors, tourmaline with his mellow autumnal hues offers superb alternatives. Turning a bi- or tri-colored tourmaline in the sun and watching his playfully change between reddish brown, yellowish green and mellow orange is most delightful!
Pure green tourmaline is a very thankful alternative to emerald and is thus often cut in baguettes and emerald shape. Tourmaline comes in good sizes, is clean and often used as healing stone. We predict that tourmaline will gain more fame after the recent run for flashy colors has settled.
Tourmaline on photo: Mono-colored tourmaline does not cause any problems in front of the camera. His color comes out realistic and they are not too light sensitive. Multicolored stones (showing different colors in different zones) are also no challenge. But things get more difficult when it comes to bi- or tri-colored stones. Sometimes it is possible to capture all colors in one angle. But more frequently the photographer gets sore fingers and a heart attack before he leaves it to the grader to describe the color play in words.
Natural untreated topaz is rarely available, and a lot of consumers buy all kinds of cheap synthetics, citrine or treated and irradiated stones under the name "so-and-so-fake-topaz". This has led to much confusion and a devaluation of the original topaz. However, naturally colored topaz is an exquisite rarity and a true collector's item. Colorless topaz (which is often taken to be radiated) is a reasonable alternative to white sapphire and a good place to start a collection. The light blue stones we find in Sri Lanka are a delightful brilliant sight. Unfortunately we rarely get yellow (the "true" topaz) or pinkish topaz.
Topaz on photo: Natural colored topaz is notoriously difficult. Topaz with their naturally light colors outshine themselves and (like aquamarine) tend to look colorless even if the eye clearly captures a nice color. In any case an untreated light blue topaz is a terrific stone with a dazzling luster surpassing many much higher priced stones. I dare say, that if you see a fully colored topaz on a photo it is either heavily treated or heavily photo-shop-faked. If not, it should cost a good deal.
Chrysoberyl is yet another continent to discover. The famous color changing alexandrite is a sub-variety of chrysoberyl. Normal Sri Lanka chrysoberyls come in light to fully saturated green and fine yellow hues. They are hard and durable and thus much appreciated for jewelry. Generally of good clarity and fine luster they are a unique alternative to green or yellow sapphire.
The fabulous cat's eye is one of the miracles in the world of gemstones. Fine parallel needles throughout the stone break light in a way that the stone displays a ray moving across the stone. While garnets, quartz and other varieties might show the same effect, only chrysoberyl is correctly referred to as the cat's eye. Basic parameters to judge the ray is his definition (full and clear?), position (centered?) and his movement (flawless?) across the stone.
Chrysoberyl on photo: While faceted chrysoberyl is easy to capture, a cat's eye needs a strong single light source to display the ray. This is difficult without changing the color of the stone in the yellow tungsten light. Therefore when buying cat's eye on the web, one should also pay attention to the 'official' color description and grading.
Kornerupine is a fine new opportunity for the collector of natural colors. Until recently quasi non-existent in the gem market, kornerupine has now found attention as a nice untreated gemstone in very unique hues: From mellow green mingled with yellowish and brown tints to forest green. Depending on the cut some stones show different colors from different angels but they are not as unpredictable as tourmaline (with which they are often confused). Though kornerupine has entered the gem market only recently, we have so far always received positive feed back from those who ventured to buy this unknown variety.
Kornerupine on photo: Similar to other green stones kornerupine likes to be photographed and does neither show too good nor too bad. When it comes to his pleochroic effects, things get more difficult but since we usually try and cut him into one color, this has not been of much trouble to us.
Though soft, diopside has raised some attention from jewelry makers for his strong but reasonable priced green hues. Chrome diopside has actually become quite famous and expensive for his emerald green. However it is soft and has to be protected in jewelry. In Sri Lanka we mostly find the mellow green hues mingled with some lively yellow. Together with kornerupine, diopside make the most exciting new discovery in the world of green gems. Especially the cat's eye variety seems to have huge potential as an alternative to the more expensive chrysoberyl.
Diopside on photo: Due to his strong birefringence diopside tends to come out slightly fuzzy and light green hues present inclusions stronger that the lens shows them.