Spinel has been used in jewelry for a long time, but this gemstone has only recently been given the attention it deserves. Until the late 19th and early 20th centuries, spinel was often thought to be corundum because they are often found in the same mines. However, each of these minerals has a different chemical make-up. As a result, the reputation of the stone was hurt when people learned that some of their favorite rubies and sapphires were actually spinels. Furthermore, synthetic spinel is also cheap and common. It has been used a lot as a fake gem in class rings and birthstone jewelry, which has made people think it isn’t real. This isn’t true of spinel, which has always been a rare and beautiful gem. Spinel’s natural beauty has become more appealing to people who know how much work it takes to improve the color or clarity of low-quality rubies and sapphires. Today, almost all of the natural spinels on the market haven’t been treated. People who like them because of their low prices can buy them in almost any color and use them for most types of jewelry find them even more appealing.
|Varieties||Ceylonite, Chromite, Gahnospinel, Hercynite, Pleonaste|
|Crystallography||Isometric. Crystals octahedral; also as grains, massive.|
|Refractive Index||Varies, 1.719-1.920. See table in “Spinel Varieties” below.|
|Colors||Various shades of red, blue, green; also brown, black, gray, lilac, purple, orange, orange-red, rose, nearly colorless.|
|Fracture Luster||Vitreous to subadamantine.|
|Specific Gravity||3.58-3.98; gems 3.58-3.61. See table in “Varieties” below.|
|Luminescence||Reds and pinks: crimson in LW, also SW; red in X-rays; no phosphorescence. Blue: inert in UV. Deep purple: red in LW, essentially inert SW, lilac in X-rays. Pale blue and violet: green in LW, X-rays, essentially inert in SW. Orange, red, and pink; inert to weak red or red/orange SW. Weak to strong red and orange LW. Cobalt blue; strong chalky whitish-green SW. Inert to moderate orange or orange/red LW. Near colorless and light green; inert to moderate orange/red LW. Deep purple; red LW, inert SW. Pale blue and violet; green LW, inert SW.|
|Luminescence Type||Fluorescent, UV-Long, UV-Short, X-ray Colors|
|Enhancements||Natural spinels are usually not enhanced but may receive heat treatment. Synthetic spinels may be quench crackled.|
|Typical Treatments||Heat Treatment|
|Special Care Instructions||None|
|Transparency||Transparent to opaque.|
|Absorption Spectrum||Red and pink; Strong fluorescence between 490 and 595 nm, weak band at 656, sharp lines at 685.5 and 684 nm. May also show chromium spectrum, broadband at 540 nm, and absorption of violet. Blue; Strong band at 458 nm, narrow at 478 nm, weak lines at 443 and 433, may also have bands around 430 to 435, 550, 565 to 575, 590, and 625. Violet and purple; May show the same spectrum as blue, only weaker.|
|Phenomena||Asterism, chatoyancy, color change (rare).|
|Identifying Characteristics||Spinel minute octahedral crystals are often aligned in planes or swirls. Synthetic spinel strong ADR, cross-hatch effect. Except for red and pink, fluorescence often varies from natural.|
|Formula||MgAl2O4 + many substitutional elements.|
|Etymology||Possibly from the Latin spina for “thorn,” alluding to spine-shaped crystals. Since this is not a common habit for spinel, this origin is uncertain.|
|Occurrence||Spinels are found in metamorphic rocks and their weathering products. Especially found in contact deposits (marbles and limestones).|
|Inclusions||See “Identifying Characteristics” below.|
all but pure green and yellow
blue, dark blue
black, dark colors
|Ceylonite and pleonaste||(Mg, Fe)Al2O4||
3.63-3.90 (esp. 3.80)
very dark colors
dark green to black
deep red to black
- Red: 1.715 – 1.735
- Blue: 1.715 – 1.747
- Others: 1.712- 1.717 (normal)
SpectralThe spectra are very distinct, which helps with identification.
The chromium spectrum, which includes a broad band at 540 nm as well as violet absorption, is red and pink. Fluorescent “organpipe” lines could be a group of fine red lines.
Blue: There are blue lines in the iron spectrum, particularly at 458, as well as a narrow line at 478 and weak lines at 443 and 433. 686, 675, as well as 635, 585, 555, and 508, are the two most powerful. (Note that this iron spectrum differs from synthetic spinel’s cobalt blue.) Bands of 700 and 570 in Nigerian blue gahnite are similar to those found in spinel. The spectrum of mauve and pastel blue is similar to that of blue, except it is weaker.
InclusionsIn general, spines are free of inclusions, although some inclusions stand out. Silk is rarely visible in spinel, as it is in sapphires and rubies. There are angular inclusions known as spangles. The unique rows and swirls of small octahedra of another spinel, such as magnetite (Fe3O4), are visible. Iron-stained films and feathers, particularly near gem margins, zircon inclusions and darkening surrounding areas, and zircon haloes (owing to radioactivity) with feather around zircon due to stress cracking are also common. Natural spinels have octahedron-shaped cavities (negative crystals) that are occasionally filled with calcite. Calcite, apatite, dolomite, and olivine may be found in specimens from Mogok, Myanmar. Zircon, sphene, baddeleyite, phlogopite, apatite, and spinel may be found in Sri Lankan specimens.
SyntheticsAuguste Verneuil created the flame fusion process for creating synthetic sapphire in the late 1800s, and it can also be used to make spinel. Colorless spinels are almost certainly man-made. (There are also very light, almost colorless natural specimens, in addition to the extremely rare colorless natural spinels.) These colorless synthetics are excellent diamond imitators. It can be difficult to tell the difference between natural blue stones containing cobalt and flux-grown or flame-fusion synthetics. Flame fusion synthetics, on the other hand, frequently exhibit chalky, pale green fluorescence in SW UV and bright red fluorescence in LW UV. In cross-polarized light, these synthetics also exhibit “crosshatched” or “snakelike” aberrant birefringent patterns. Absorption bands at 434, 460, and 480 nm are also visible in natural cobaltian spinel, but not in synthetic material. The band at 460 is particularly useful.
EnhancementsNatural spinels are usually not improved, however, they may be heated. To replicate natural fractures, synthetic spinels can be quench cracked.
SourcesSpinels have lately been discovered in Africa, Australia, Russia, and Vietnam, while they were previously only found in Afghanistan, Myanmar, and Sri Lanka. These gems are frequently mined from alluvial or placer deposits, where eroded material has been swept downstream, rather than from the hard rock main deposits where they form. In addition to spinel, these “gem gravels” may contain other species. The rough and tumble action of the gem rough has polished these crystals into spherical forms and eliminated much of the included and fragmented material. This alluvial rough is a material that is easy to recover and is ideal for faceting. The use of backhoes and hydraulic hoses for removing overburden from long-buried stream beds and supplying water for gem separation by a small crew ranges from low technology (one or more miners with straw baskets sluicing the stream gravel) to high technology (the use of backhoes and hydraulic hoses for removing overburden from long-buried stream beds and supplying water for gem separation by a small crew). Afghanistan: beautiful red spinel, the source of many ancient world huge stones. Myanmar: commonly found as perfect octahedra in gem gravels. In the Mogok morning “movie” market, a spinel crystal in marble is for sale. EighthDimensionGems.com of Bangkok photo by Jeffery Bergman. Sri Lanka: weathered pebbles in a wide range of colors, including pinks and blues; all blue pebbles contain traces of Zn; many from Sri Lanka are black. Sri Lanka is home to the rare cobaltian form. Fine blue gahnite from Jemaa, Nigeria, with an SG of 4.40-4.59 and a RI of 1.793. Gahnite from Madagascar, blue and gemmy. Gahnite is found in Australia, Sweden, and New Zealand. Kuchi Lal in the Pamir Mountains, Russia: gemmy, beautiful pink stuff. From alluvial gravels in Cambodia, Thailand, and Vietnam Japan is referred to as a galaxite. Canada, Finland, France, Germany, India, Italy, and Pakistan are among the countries represented. California, Colorado, Massachusetts, Montana, New Jersey, New York, and Virginia are all states in the United States. diamonds of spinel from all over the world 4 A collection of purple, blue, and pink African spinels, a top red Myanmar gem, an African lavender stone, a pink specimen from Russia, a “padparadscha” colored African piece, and an opaque black stone. Barbara Smigel of Artistic Colored Stones provided the image.
Sizes of StonesSpinels can range in size from a few carats to hundreds of carats and come in a variety of colors. 45.8 (light purple, Sri Lanka); 36.1 (indigo blue, Myanmar); 34 (red, Myanmar); 29.7 (red, Myanmar) Smithsonian Institution, Washington, DC (pink-violet, Sri Lanka). Deformed red octahedron from Sri Lanka, 520; another crystal, 355. British Museum of Natural History, London, England: deformed red octahedron from Sri Lanka, 520; another crystal, 355. 11.25 in a private collection (Sri Lanka, superb cobaltian gem, intense blue emerald-cut). Fine red gem, 105, Louvre, Paris, France. New York’s American Museum of Natural History: 71.5 (red, Sri Lanka). “Black Prince’s Ruby,” red spinel, estimated at 170; “Timur Ruby,” red spinel, 361. Crown Jewels of England: “Black Prince’s Ruby,” red spinel, estimated at 170; “Timur Ruby,” red spinel, 361. Fine red gem, over 400 carats, from the Diamond Fund in Moscow, Russia. Banque Markazi, Teheran, Iran: red stone with a value of over 500, another with a value of over 200, and another with a value of over 225.
TrademarksRed spinels were once known as “balas rubies,” after Balascia, the historical name for the territory that is today split between Afghanistan and Tajikistan. This was a significant source of these precious stones. Although spinels were once mistaken for rubies and sapphires, they are now recognized as separate gemstones. Any references to “spinel ruby” or “spinel sapphire” that you may come across today are incorrect. Arizona spinels, which are red or green garnets, are occasionally referred to incorrectly as “Arizona spinels.” Almandines are sometimes referred to as “candy spinels,” which is a misleading term. For further examples, see our List of False or Misleading Gemstone Names. Spinels are strong and durable gemstones that don’t require any extra cleaning or care.
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1. History of Gemstones
Gemstones Formation1. Igneous 2. Metamorphic 3. Sediment 3. Hydrothermal
EgyptI think most people think of the Egyptians when they think of old jewelry. It was only when the tomb of Tutankhamun was opened in 1922 that the hieroglyphs were seen for the first time. They show people wearing gold bangles, neckpieces, and earrings. One of the most amazing things about this almost-complete tomb was that it had a lot of beautiful, gold-covered artifacts. The Egyptian aesthetic has been a big influence on Modernist jewelry, and it still has a big influence on jewelry designs today. Germany A fibula-brooch or pin that is used to fasten clothes, usually on the right shoulder. The fibula came in a lot of different shapes, but they all used the same safety-pin idea. Fibulae aren’t just pretty like most modern brooches. They were used to fasten clothes, like cloaks, back then. Archaeologists use the word “fibula” when they talk about ancient jewelry. They also use the word “brooch” when they talk about jewelry from the British Isles, and when they talk about other types of jewelry that aren’t old “safety pin” types.
IndiaAt that time, navaratna was first used. As it turns out, India’s history of diamond mining and pearl fishing goes back more than 2,000 years. In ancient times, a lot of its coastline was protected by huge coral reefs. Today, only the eastern state of Orissa makes ruby, sapphire, emerald (beryl), garnet, topaz, zircon, and cat’s-eye chrysoberyl, all of which come from the same place. The gems of navaratna are a way to show off the natural treasures of this ancient civilization.
2. Hidden treasures of Sri LankaSapphires are the best gems to buy from Sri Lanka as an investment.
3. Healing power of gemstones
3. How to become a gem trader?You could be able to, 1. Identify 2. Valuate 3. Trade Also should practice selling methods Ex : A.For the beauty B.For the wealth C.As an Investment and protect money D.As astrological and helping purpose Identify sources A.Gem mines B.Gem Fairs C Gem Sellers
ValuationYou must study the market with a professional to speed up the process. If not it takes a long time to evaluate row gems, cut and polished gems, and invest in proper gems.
TradingYou should only invest in investor-grade gemstones with reseller value. That process also could only be speed up by a professional trader. You can sell in the local market or in the international market. The best way is gem mine to end customer. Find end customers to make maximum revenue. Thank you Sampath Samarasekara the Gemological Institute of Ceylon[learn_press_profile]
|Varieties||Hyacinth, Starlite ,Etc..|
|Crystallography||Tetragonal. Crystals prismatic, pyramidal; often twinned; rounded pebbles.|
|Refractive Index||Varies by the amount of radioactive damage to its crystal structure. Low (most damaged): 1.78 – 1.85; Intermediate: 1.85 – 1.93; High (least damaged): 1.92 – 2.01. See “Varieties” for more information.|
|Colors||Reddish-brown, yellow, gray, green, red; various other colors induced by heating.|
|Luster||Vitreous to adamantine; sometimes greasy.|
|Polish Luster||Vitreous to adamantine|
|Fracture Luster||Vitreous to subadamantine|
|Hardness||6 (Low), 7.5 (High)|
|Specific Gravity||Low 3.95-4.20, Intermediate 4.08-4.60, High 4.60-4.80|
|Birefringence||Varies by the amount of radioactive damage. 0 (isotropic)-0.059. See “Varieties” for more information.|
|Dispersion||0.039 for all zircon types.|
|Luminescence||See “Identifying Characteristics.”|
|Luminescence Type||Fluorescent, Phosphorescent, UV-Long, UV-Short, X-ray Colors|
|Enhancements||Virtually all blue zircon is heat treated.|
|Typical Treatments||Heat Treatment|
|Special Care Instructions||Facet edges wear off. Use protective settings for ring use.|
|Transparency||Transparent to opaque.|
|Absorption Spectrum||See “Identifying Characteristics.”|
|Formula||ZrSiO4 + Fe, U, Th ( Zirconium Silicate )|
|Pleochroism||Distinct in blue stones: deep sky blue/colorless to yellowish gray. Red: red/clove brown. Brown: reddish-brown/yellowish-brown.|
|Optic Sign||Uniaxial +|
|Etymology||From the Arabic zargun, from the Persian zar for “gold” plus gun for “color.” The name is ancient.|
|Occurrence||In igneous rocks worldwide, especially granites. Also found as alluvial material.|
|Inclusions||Angular zoning and streaks are sometimes seen in the low type. Some silk is seen occasionally, as well as tension cracks and epigenetic cracks stained with iron oxides. Metamict pieces may have bright fissures known as angles.|
It’s true that zircons aren’t just fake diamonds. They’re also more than just that. They’re beautiful stones in their own right, and they come in a wide range of colors that are found in nature. Heat treatments also make a lot of new colors.
The names for Zircons
*Hyacinth or jacinth is a type of transparent reddish-brown zircon. This name was also used for hessonite, which is a reddish-orange variety of garnet.
Misleading NamesZircons that don’t have any color have been sold as “Matara” or “Matura diamonds” and “Ceylon diamonds.” Zircons can be used to make diamonds look like diamonds, but selling them as real diamonds is unethical. Blue zircons have been sold as “Siam aquamarines,” but they aren’t. Zircons are rarer than both diamonds and aquamarines, but these gems are more popular than zircons, even though they are rarer. Thus, some dishonest people will use these names to sell zircons more quickly. You can see a list of gemstone names that aren’t true or that aren’t very clear.
Radiation and the Properties of Zircon They get a little bit of radioactive uranium and thorium as they grow. This radiation can’t be seen or heard. In time, the crystal structure is broken down by a lot of radiation, but not all at once. These stones, which are usually green, change color. Those are materials that no longer have crystals in them because radiation has made them more amorphous than they used to be. They have a lower RI and more sparkle than crystallized zircons.People put zircon into one of three groups based on how bad it is going to get. High, immediate, medium, or low. These are also called alpha, beta, and gamma, but they aren’t the only types of brain cells. The classes are easy to tell apart because the properties change in an even way. All of the zircon in high zircon is crystal clear and has the best properties. Intermediate zircon is a material that has been slightly damaged by radiation. A lot of zircon is metamict. ( A mineral whose crystal structure has been disrupted by radiation from contained radioactive particles ) It’s interesting that dispersion is the same for both high and low types, but other optical properties are different. The texture of low zircon is often cloudy.
The most obvious way to tell a zircon diamond from a real diamond is by the former’s birefringence.All types of faceted zircon can be identified by having worn or abrased facet edges.
The fluorescence of zircon can be different. Some things aren’t useful. Other crystals light up very brightly. Mustard yellow and yellow-orange are two of the most common colors that glow under shortwave ultraviolet (UV) light. There is some zircons that glow dull yellow in longwave (LW) UV light. They may also phosphoresce, which makes them look like fireworks. When zircon is looked at with X-rays, it can be white, yellow, green, or violet-blue.
- Red to orange-red: inert to strong, yellow to orange (SW).
- Yellow to orangish-yellow: inert to moderate yellow to orange (LW and SW).
- Green: usually inert.
- Blue: inert to moderate, light blue (LW).
- Brown: inert to very weak red (SW).
A method called flux has been used by scientists to make crystalline zircons for research, so they can learn more about them. However, there is no known use for this lab-made material in jewelry. However, you may be able to buy “synthetic zircons” online. It’s not clear if this material is made in a lab or if it’s cubic zirconia, which is more common and well-known (CZ). Zircons and cubic zirconia have both been used to look like diamonds, but they’re two different types of gems. While the CZ used in jewelry is made in a lab, it’s not synthetic zircon.
Zircons that don’t have any color or blue have almost always been heated. This procedure is not going to be found. Heating is the most common way to make blue, colorless, and golden-yellow shades. The stones that make these beautiful colors are usually reddish-brown in color. People don’t usually heat treat zircons that aren’t the same color. Green and yellow colors made by heating are usually more stable over time and less likely to fade from sunlight and UV light than blues made by heating.Heating helps to crystallize zircons that aren’t completely clear. This increases the specific gravity and makes the absorption spectrum more focused. People who heat green Sri Lankan zircon make it look a little less green in color. Sri Lankan material that is reddish-brown turns colorless, sometimes reddish violet. A lot of people like to heat red-brown Thai and Cambodian stones so that they become colorless, blue, or golden. Often, brownstones are heated with or without oxygen in them to make them look blue and yellow. Brown zircons with a lot of uranium may turn green when they are heated.
SourcesZircon can be found all over the world, but crystals that are good enough to be used as gems are rare. Sri Lanka and Southeast Asia are the main sources of zircons that are good enough for jewelry. Sri Lanka makes gravel in all kinds of colors, including rare cat’s eyes. Cambodia is the chief source of material that heat treats to colorless and blue. Myanmar produces yellowish and greenish stones in gem gravels with ruby. These stones have complex absorption spectra. Thailand is one of the most important commercial sources of gem-grade zircon. Other notable gem-quality sources include the following localities:
- New South Wales, Australia: fine gem material (orange).
- Quebec and Ontario, Canada: dark, opaque crystals up to 15 pounds, yield only tiny gems.
- France: red crystals at Espaly, St. Marcel.
- Emali, Tanzania: white zircon pebbles.
- United States: Colorado; Maine; Massachusetts; New Jersey; New York; Oklahoma; South Dakota; Texas.
- Brazil; China; Germany; India; Madagascar; Mexico; Nigeria; Norway; North Korea; Pakistan; Russia; South Korea; Vietnam.