Abundance of Type II Diamonds

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Science  08 Sep 1967:
Vol. 157, Issue 3793, pp. 1173-1175
DOI: 10.1126/science.157.3793.1173


More than 1300 natural microdiamonds, mostly averaging 0.0015 carat, were studied for transparency to ultraviolet radiation, λ2537. Of most of them, of this size, 16 percent were completely transparent (presumably type II); 27 percent, completely absorbent (presumably type I). The remainder transmitted partially. The number of type-II diamonds is unexpectedly very high; a considerable proportion of microdiamonds may begin life as type II, later incorporating absorbent type-I material.