Garnet Citrine
How Gems Are Formed?????????????
Hi, please could somebody tell me how these minerals are formed:
Amethyst
Citrine
Gypsum
Pyrite
Garnet
Hematite
Ladorite
Argonite
If you know just one or a website please post it
Thanks
If you know anyone then please post
amethyst is a good general example.
its quartz that has a trace amount of iron in it.
as a high pressure hot silica slurry slow cools, atoms of silicon dioxide start losing kinetic energy and drop into lock-step with each other, forming a crystal, if there is a trace of iron in the slurry, the crystal will be purple instead of clear... if the iron gets used up, the crystal will go from purple to clear.... sometimes purple to yellow, forming crystal of citrine.
Sri Lanka and Its Gems
Sri Lanka has long been known for its richness in gems. In fact, it was the first information about Sri Lanka that came to Europe: "An island on which the rivers are filled with gems." That, of course, is somewhat exaggerated, but the pioneers of those days needed good reasons to leave home for years on end, to convince investors and to get sailors to sign up for the long and dangerous trip. At any rate, it is true: Sri Lanka is blessed with rare earths. Only after the discovery of gemstone deposits on Madagascar could any country compete with the abundance found in Sri Lanka. But since the Madagascan gem trade is dominated by Sri Lankans, this did not harm Sri Lanka's image gem trade in any way.Since a lot has been said about the famous rubies and sapphires, we would like to offer some insight into the 'new' varieties that lately entered the gem market mainly via the Internet. With regard to the fact that these stones are widely bought based on photos, I have also added some remarks on how these less popular varieties behave in front of the camera.
Spinel: Spinel 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. 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.
Garnet: Fairly priced and full of surprises.
Pyrope: Pyrope is typically described as blood or wine-red, while this 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. In photos, 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: 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, hessonite is currently found in Sri Lanka 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. Although hessonite is wonderful to look at in person, 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 ignore the fuzziness of the photo. If you like the color you will have to test the luster in person.
Almandine: 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 the 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 still a fine deal compared to the price of a similar color thrill in spinel or ruby. The needle structure in almandine tends to look a bit fizzy on photos. Nevertheless, almandines are a pleasure to shoot - 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 & raspberry garnets: 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. 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.
Color change garnet: 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 alexandrite, but somewhere down the supply chain somebody has a bad awaking with them. On the other side, one must ask, why does 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, hunt the last color change garnets before the deposits are depleted. 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 cheap color changers. A color change that is fully visible on photo without photoshop tricks is truly rare and will never be cheap (at least not in natural stones).
Zircon: 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 could it be misused as an imitation for diamonds). Its brilliance and luster is unbeatable and its high birefringence is most unique. Naturally colored zircon can be green, yellow, brown, (rarely) blue, (very rarely) red and often colorless. In any color, it 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. As a rule, zircons are even better in person than their images. The birefringence of zircon is so dominant that it 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. Of course, 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.
Aquamarine: Unfortunately, we do not get many aquamarines in Sri 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 for unique stones. Light colored stones are notoriously difficult to capture in photos. 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, it might in the photo show nearly colorless. Light colors also make inclusions look much more serious on the photo than in reality. Again, trust the seller not the photo.
Amethyst: Amethyst is a 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 no problem in photos. Amethyst is grateful in front of the camera and makes easy realistic shots.
Tourmaline: 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 can be an 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. Mono-colored tourmaline does not cause any problems in front of the camera. The 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.
Topaz: Natural untreated topaz is rarely available, and a lot of consumers buy all kinds of cheap synthetics, citrine or treated and irradiated stones. 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. Natural colored topaz is notoriously difficult to photograph. 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. 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 fortune.
Chrysoberyl: 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 the definition (look for full and clear), position (should be centered) and the movement (should be flawless) across the stone. 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: 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. Similar to other green stones kornerupine likes to be photographed. When it comes to pleochroic effects, things get more difficult. Since stones are cut him one color, this should not be much trouble.
Diopside: Though soft, diopside has raised some attention from jewelry makers for its strong but reasonable priced green hues. Chrome diopside has actually become quite famous and expensive for its 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. Due to his strong birefringence, diopside tends to come out slightly fuzzy and light green hues present inclusions stronger that the lens shows them.
Sinhalite: Sinhalite is the Sri Lankan stone (in regard to the origin of the name). It is usually found in fine yellow brownish colors and highly priced in honey yellow. Sinhalite is a rare collector item that was identified only a few decades ago. Though uncommon in jewelry, it has all the qualities to be mounted and we would love to see more of it. As long as the color is not too light, sinhalite poses well in front of the camera.
About the Author
Edward was born in 1968 in Berlin. His family migrated to Sri Lanka in 1973. He studied biology and international development in London and Berlin. His company, Wild Fish Gems was founded in 2000 as a company specializing in Ceylon gems that have not been treated with radiation, chemicals or heat. He has recently begun sourcing from a broader range of countries across Southeast Asia and Africa. His gemstones are delivered daily to jewelers and gem lovers all over the world. Visit www.wildfishgems.com for more information.
