Gemstones -

: A broad category for all other stones, including Amethyst , Topaz , and Opal . Organic Gems : Non-minerals like Amber , Pearl , and Jet . The "4 Cs" of Gemstone Value

: Evaluated by its hue (the basic color), tone (lightness/darkness), and saturation (intensity). GEMSTONES

Gemstone Buying Guide - The National Association of Jewellers : A broad category for all other stones,