IaB 鑽石     

文：杜雨潔

今晚...想來點....Ia 加 IIa

多重人格的鑽石是有的. 就來個更稀少的亞種吧!

所以Ia型的鑽石裡面又有 IaA, IaAB, IaB

Ia 型鑽石是氮很喜歡打混在一起的鑽石，不過又喜歡搞小圈圈聚集，這可以分為其他亞種。當這些聚集體在金剛石晶格內成對出現時，稱為 IaA 型。 當它們以 4 個氮原子的聚集出現時，被歸類為 IaB 型。這些類型不能吸收任何波長的可見光。也就是說有氮，但又搞神秘。

然而，當氮以丸子三人組（也稱為 IaN3 型中心）出現時，氮三人組會吸收光譜藍色端的可見光，導致鑽石中出現常見的黃色調。

因此，IaB 型鑽石中的氮不會影響鑽石的顏色， 可以說是隱藏版的極白鑽    

在GIA鑽石證書的附件可能還會看到一種稀有的~ IaB

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GIA彩色鑽石分級證書的鑽石類型分類 #12345678

科學家基於氮的存在與否將鑽石分為兩種主要”類型” — I 型和 II 型，氮可以佔替鑽石原子結構中碳原子的位子。這兩種鑽石類型可以根據其化學和物理特性的差異進行區分。I型鑽石在紅外吸收光譜中含有可檢測量的氮，它們被細分為四組（Ib、IaA、IaAB 和 IaB），取決於鑽石中氮的聚集狀態。

根據 GIA 鑑定所的記錄，GIA 鑽石分級報告書 #12345678 中描述的 6.58克拉橢圓形混合式鑽石鑑定確定為IaB 型鑽石。IaB 型鑽石是非常稀有的品種，佔所有寶石級鑽石中不到1%。IaB 型鑽石中的氮濃度通常低於其他I型鑽石種類，它們的氮型態為完全聚集形成B中心，即四個氮原子圍繞一個空位。根據鑽石及對其內含物的科學研究，與其他大多數寶石級鑽石相較下，許多IaB型鑽石很可能源自地球地函(地幔)深處，地函深部的極高溫度被認為有利於氮的聚集得以形成IaB 型鑽石。

出自博茨瓦納Botswana卡羅威Karowe礦，命名為星宿之石Constellation的 812.77克拉毛坯鑽石，即為著名的IaB型鑽石典型的實例。

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Diamond type classification for GIA colored Diamond Grading Report #....

Scientists classify diamonds into two main "types"- type I and type II - based on the presence or absence of nitrogen which can replace carbon atoms in a diamonds atomic structure. These two diamond types can be distinguished on the basis of differences in their chemical and physical properties. Type I diamonds contain detectable amounts of nitrogen in infrared absorption spectroscopy and they are subdivided into four groups (Ib, IaA, IaAB, and IaB), depending upon the aggregation states of nitrogen in the diamond.

According to the records of the GIA Laboratory, the 6.58 carat Oval Brilliant diamond described in GIA Diamond Grading Report #203942034890293 has been determined to be a type IaB diamond. Type IaB diamonds are a very rare variety, accounting for less than 1% of all gem diamonds. Nitrogen concentrations in type IaB diamonds are generally low relative to other type I diamond varieties, and their nitrogen is fully aggregated to form B centers, which are groups of four nitrogen atoms surrounding a vacancy. Based on scientific studies of diamonds and their mineral inclusions, it is likely that many type IaB diamonds originate from deeper in the earth’s mantle compared to most other gem diamonds. The very high temperature in the deep mantle is thought to facilitate nitrogen aggregation and develop type IaB diamonds.

The 812.77 carat rough diamond, named the Constellation, from the Karowe Mine in Botswana is a good example of notable type IaB diamond.