Trigons are a testimony of Nature’s power, a sign of uniqueness and a part of the gemstone’s history.

Gemmologically speaking, trigons are triangular shaped growth marks or etch marks on the surface of natural diamonds. When found on an octahedral crystal, trigons point in the opposite direction to that of the crystal face and are indented. This seems to happen due to chemical dissolution, while the stone is still in the Earth, either in the mantle where it forms, or in other parts of the Earth while it is brought up to the surface. Those triangular pits can also be called etch marks or etch pits as they are indented in the surface of the crystal. Trigons can also be found pointing in the same direction as the crystal face, and in that case they are raised above the surface. Those, mostly happen during the growth of the diamond and therefore referred to as growth marks. We call them positive and negative trigons.

If found on diamonds, those triangular features are a strong sign of a natural gemstone, however, some synthetic flux grown spinelshave been seen bearing trigons as well, as reported by the SSEF in 2008.