This paper gives a simplified calculation of the valence band structure for a diamond-type crystal in nearest neighbor approximation.

用最近邻近似法对金刚石型晶体的价带给出了一种简化的计算法。

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It features a pear-shaped D color, type IIa diamond of 15.31 cts. and VVS2 clarity before.

FORBES: 30.52-ct. emerald-cut diamond sold for $3.3 million.

Gemesis colorless diamonds are all certified as Type IIa, the purest type of diamond, almost or entirely devoid of chemical impurities.

FORBES: Gem-Quality White Diamonds Created in Laboratory

Adding to their allure is that they have also been determined to be Type IIa, the most chemically pure form of diamond showing exceptional appeal transparency.

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