Tatami structure in synthetic diamond

The anomalous birefringence that we can see in some diamonds between polaroids can give us additional information about its nature, since it shows us structural deformations produced in the crystal during its growth. The characteristic structure that we see in photographs of parallel lines in two crossing directions is also known as “tatami”, and it is very common to find it in CVD synthetic diamonds. However, we must be careful since a pattern like this can also be observed in type IIa natural diamonds.