14.96 CTS ALEXANDRITE - SPECIMEN FROM TANZANIA [S-SAFE250]
- 存货单位
- 尺寸(毫米)
- 14.000 x 9.000 x 6.000mm
- 重量 (cts)
- 14.960
- 类型
- Specimen
- 颜色
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ALEXANDRITE SPECIMEN
This is a natural untreated Alexandrite specimen from Tanzania which i bought from the miner on my last trip there. They are not suitable for faceting but can be cabbed or kept as a specimen.
The most sensational feature about this stone, however, is its surprising ability to change its colour. Green or bluish-green in daylight, alexandrite turns a soft shade of red, purplish-red or raspberry red in incandescent light. This unique optical characteristic makes it one of the most valuable gemstones of all, especially in fine qualities.
Alexandrite is very scarce: this is due to its chemical composition. It is basically a chrysoberyl, a mineral consisting of colourless or yellow transparent chrysoberyl, chrysoberyl cat’s eye and colour-changing alexandrite (also in cat’s eye varieties). It differs from other chrysoberyls in that it not only contains iron and titanium, but also chromium as a major impurity. And it is this very element which accounts for the spectacular colour change. Rarely, vanadium may also play a part. According to CIBJO nomenclature, only chrysoberyls displaying a distinct change of colour may be termed alexandrite.
Like many other gemstones, alexandrite emerged millions of years ago in a metamorphic environment. But unlike many others, its formation required specific geological conditions. The chemical elements beryllium (a major constituent in chrysoberyl) and chromium (the colouring agent in alexandrite) have contrasting chemical characteristics and do not as a rule occur together, usually being found in contrasting rock types. Not only has Nature brought these contrasting rock types into contact with each other, but a lack of the chemical element silica (the second most common element in the Earth’s crust) is also required to prevent the growth of emerald. This geological scenario has occurred only rarely in the Earth’s history and, as a result, alexandrite crystals are very scarce indeed.
- 存货单位
- 尺寸(毫米)
- 14.000 x 9.000 x 6.000 mm
- 重量 (cts)
- 14.960
- 类型
- Specimen
- 颜色
-
ALEXANDRITE SPECIMEN
This is a natural untreated Alexandrite specimen from Tanzania which i bought from the miner on my last trip there. They are not suitable for faceting but can be cabbed or kept as a specimen.
The most sensational feature about this stone, however, is its surprising ability to change its colour. Green or bluish-green in daylight, alexandrite turns a soft shade of red, purplish-red or raspberry red in incandescent light. This unique optical characteristic makes it one of the most valuable gemstones of all, especially in fine qualities.
Alexandrite is very scarce: this is due to its chemical composition. It is basically a chrysoberyl, a mineral consisting of colourless or yellow transparent chrysoberyl, chrysoberyl cat’s eye and colour-changing alexandrite (also in cat’s eye varieties). It differs from other chrysoberyls in that it not only contains iron and titanium, but also chromium as a major impurity. And it is this very element which accounts for the spectacular colour change. Rarely, vanadium may also play a part. According to CIBJO nomenclature, only chrysoberyls displaying a distinct change of colour may be termed alexandrite.
Like many other gemstones, alexandrite emerged millions of years ago in a metamorphic environment. But unlike many others, its formation required specific geological conditions. The chemical elements beryllium (a major constituent in chrysoberyl) and chromium (the colouring agent in alexandrite) have contrasting chemical characteristics and do not as a rule occur together, usually being found in contrasting rock types. Not only has Nature brought these contrasting rock types into contact with each other, but a lack of the chemical element silica (the second most common element in the Earth’s crust) is also required to prevent the growth of emerald. This geological scenario has occurred only rarely in the Earth’s history and, as a result, alexandrite crystals are very scarce indeed.
运输商 | 运送至:国家 | 运送到世界其他地区 |
---|---|---|
FedEx | $12.00 / :几天天 | $39.00 / :几天天 |
:国家
FedEx折扣至$12.00 ,适用于包含2或更多商品的订单
世界其他地区
FedEx折扣至$39.00 ,适用于包含2或更多商品的订单
|
||
Registered Shipping | $9.00 / :几天天 | $16.00 / :几天天 |
:国家
Registered Shipping折扣至$9.00 ,适用于包含2或更多商品的订单
世界其他地区
Registered Shipping折扣至$16.00 ,适用于包含2或更多商品的订单
|
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积极的
Good stone great service
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积极的
Great thank very much, lovely pearls.
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积极的
Nice piece of rough. thankyou
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积极的
Nice stone. Thankyou
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积极的
Have received the rough. Nice colour. Thankyou
审计
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描述准确
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图片准确
Comments
The Verified Seller has provided accurate and honest pictures and details for this listing. Gem Rock Auctions is committed to holding our sellers to the highest standards of integrity and transparency. As part of this policy, we only permit the sale of natural, earth mined, gemstones. Many Gemstones have received treatments to enhance their color or clarity to further emphasize their beauty and we insist treatments are disclosed. Manmade, synthetic, and imitation gemstones are not permitted on Gem Rock auctions.