Diamond Properties : Trigons

The triangular etch pits seen on the natural surfaces of a diamond. A trigon's points are aligned towards the edges of the crystal's octahedral faces. Similar etch markings include rectangles, squares, or parallel lines. As with trigons they are often intentionally left intact to aid diamond cutting and can be seen under high magnification, usually along or adjacent to the finished stone's girdle.

The diamond octahedron has the shape that we describe as a diamond. While it is the most common shape for a diamond crystal, cubes, dodecahedra, and combinations of these three shapes are common. All are highly symmetrical, with equal dimensions in three perpendicular directions, and all are manifestations of the cubic crystal system to which the mineral

Exceptions are the flat form called a macle, which is a twin, or composite crystal, as if mirrored across the middle, and etched crystals, with rounded surfaces and, sometimes, elongated shapes. The shapes of diamond crystals can be very intriguing.

The triangles result from subtle changes in height on a diamond's octahedron face and are called trigons. The trigons shown here are indentations, probably produced by natural etching of the crystal.

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.

Other Properties of Diamond.