The Formation of Trigons on Diamonds

The results of observations on trigons on octahedral faces of diamonds are given. Imperfect steps are believed to be present on the growing surfaces and to cause the trigons to be formed. These steps are assumed to be formed as a result of accumulation of interstitial faults in the lattice. Further, it is shown that trigons are formed mainly below a certain temperature, characteristic to the growing face and to the imperfect steps on it. This temperature should be lower than the transition temperature for the same face on a perfect crystal, and seems to be thus reduced to temperatures at which the crystals might have been grown. The theory accounts for the observed characteristics of the trigons.