The Qualities of a Gem Diamond

The brilliance and fire of a gem diamond result from it's properties of refraction, reflection, and dispersion. Upon passing through a diamond facet (one of many small planes cut onto the gem surface), a light ray is refracted, or bent. The bent ray is reflected from bottom facet upward through a top facet. In refraction each color of the ray is bent at a slightly different angle. This spreading of colors is called dispersion. Since refraction occurs both as the ray enters and as it leaves the diamond, dispersion also occurs twice. Thus the ray is emitted as a glittering rainbow. Of all gems the diamond has the highest property, or index, of refraction.

Most diamonds are tinged with color. If a diamond's color is sufficiently intense, it is prized as a gem and called a "fancy". Blue and pink diamonds are the most valuable. Red diamonds are very rare. Clear white diamonds are called diamonds of the first water.