This image of trigons was created with Nomarski differential interference contrast microscopy and is 0.29 mm across. Real diamond crystals don't have completely smooth faces.
Trigons are triangular growths that reflect subtle changes in height on a diamond's face.
The trigons shown here are slight indentations that were most likely produced by a natural etching of the crystal. However, raised trigons, which point in the same direction as the crystal face, may also occur from etching, dissolution, or as part of the natural growth of the crystal.