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12.35 CTS ALEXANDRITE - SPECIMEN FROM TANZANIA [S-SAFE252]

4722
15

SKU
寸法(mm)
14.000 x 9.000 x 5.000mm
重さ (CT)
12.350
タイプ
Specimen

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.

配送業者 配送先Australia その他の国への配送
FedEx $12.00 / 3 $39.00 / 10
:国
FedEx 、 2以上のアイテムを含む注文で$12.00に割引されます
世界のその他の地域
FedEx 、 2以上のアイテムを含む注文で$39.00に割引されます
Registered Shipping $9.00 / 7 $16.00 / 21
:国
Registered Shipping 、 2以上のアイテムを含む注文で$9.00に割引されます
世界のその他の地域
Registered Shipping 、 2以上のアイテムを含む注文で$16.00に割引されます

sedagems
sedagems
Hi Welcome to the Sedagems store, Run by Paul Sedawie and specializing in Australian sapphires and gems stones he has collected on his many buying trips world wide. All stock has a money back guarantee as your continued business is our business.
Mermaid Waters 、 Australia
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19054フィードバック

  • martin11
    martin11
    ポジティブ

    Great thank very much, lovely pearls.

  • philsgems
    philsgems
    ポジティブ

    Nice piece of rough. thankyou

  • philsgems
    philsgems
    ポジティブ

    Nice stone. Thankyou

  • philsgems
    philsgems
    ポジティブ

    Have received the rough. Nice colour. Thankyou

  • ryumaru
    ryumaru
    ポジティブ

    Beautiful ametrine. Very fast delivery. Professional seller

5%
クーポンコード SEDADEALS
まで有効
2nd Jan 2025

監査

この製品はGemstone Sheriffによって監査され、次のことが判明しました:
  • 説明が正確
  • 正確な写真

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.

この監査は1ヶ月前にリクエストされました
最終更新1ヶ月前

発送詳細

配送:
$16.00 21日 ( Registered Shipping経由)
発送元:
Australia

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この販売者は、 Australiaでの取引に10.00%税金を追加します。

概要

リストタイプ : Standard
製品番号 : 862246
始まります : 19th December 2024 06:03 pm PST
* すべての価格はUSDで表記されています