Cut actually means two: the shape of the diamond (round, marquise, pear, oval, heart, emerald, princess radiant) and the proportions of the stone. When a stone is cut to good proportions, light is reflected from facet to facet, then dispersed through the top. The better the cut, the greater the sparkle, brilliance and fire of the stone. 

Most diamonds look colorless. But there are many subtle shade differences that range from colorless to yellow/brown. Diamonds are graded on a color scale that ranges from D (colorless) to Z (yellow/brown). Diamonds with no hint of color at all are extremely rare and therefore, more valuable. Most gem quality stones appear to be colorless, but they usually have at least a hint of color.

Almost all diamonds contain a combination of internal and external characteristics called inclusions and blemishes. Normally, they are too minute to be visible without powerful magnification. Some are even so small they require great skill and time to locate. The number, type, location, visibility and color of inclusions determine a diamond's clarity and may influence its value.