A.L.M.T. Corp.

What are Diamond/CBN?


Diamond comes from the Greek word "adamas" (a thing hard to be conquered) and became “Diamond" in the middle of the 16th century. The Japanese name is Kongoseki. It is a mineral made of pure carbon, generally known as a gem. Because it is the hardest among natural substances, it is also used for industrial applications.

Approximately 80% of all natural diamond is used for industrial applications; nearly all artificial diamond is for industrial applications. Synthetic diamond, also called artificial diamond, is diamond artificially created using carbon materials. The synthetic diamond is mainly produced by high temperature, high pressure synthesis (HPHT) or chemical vapor deposition (CVD).

Synthetic diamond is far inferior to natural diamond in terms of transparency and radiance. In addition, it is greatly inferior in terms of beauty derived from diamond’s refractive index of light. Synthetic diamond, therefore, is mostly used for industrial applications, not for jewelry.

Synthetic diamond

Synthetic diamond
(Sumitomo Electric Co., Ltd. Sumicrystal®)


CBN is an acronym for “cubic boron nitride,” constitute of boron and nitrogen.

CBN has the high hardness of diamond. Compared to diamond, which starts oxidation at 700 ° C, CBN has a thermal tolerance up to 1,300°C , so CBN is superior for high temperature processing.

Comparison of Diamond/CBN and abrasive grain for general whetstones

(1)Thermal Conductivity
Thermal Conductivity
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