For different gemstones, the ideals of color are different. For a diamond, it is generally considered that the best color is no color!. Clearly, this is not true for rubies, sapphires, emeralds, etc. Colour usually is graded either in north daylight, in a room free from colour reflections or by using an instrument or standards.

CUT:

An important part of the beauty of a cut stone is its sparkle! In detail, this is due to "brilliance" and "fire" (both of which are covered later in this module).

In order to achieve brilliancy and fire, the proportions of the diamond must be appropriate so that flashes of light (brilliance) and fire (color, especially important in diamonds) are seen and the stone does NOT look dull. Some work has been put into finding the ideal proportions for each gem stone. The concepts used to determine these will be discussed later in the module. A poorly cut stone will not have the ideal proportions (angles between facets, widths of facets) and may be poorly polished.

CLARITY

In almost all cases, it is desired that gemstones are free of inclusions and surface blemishes. Clarity is related to the size and number of inclusions. For diamonds, the clarity is rated on a scale of flawless to imperfect. To determine a diamond's clarity, it is usually viewed under 10-power magnification. Large inclusions can cause a stone to be prone to breakage.