As with all gemstones, sapphires which are "clean" and have few visible inclusions or tiny flaws are the most valuable. However some very fine sapphires, in particular those from Kashmir, have a velvety mist look to them which enhances the richness of the blue.

Sapphire clarity is measured using a jeweler's loupe under 10X magnification. Sapphires are considered a Type II gemstone, which include gemstones that tend to be "eye clean" but normally have a few inclusions.

Related to sapphire clarity is transparency. For more information, see sapphire transparency.