Peridot

Peridot is the gem-quality version of olivine which occurs in volcanic basalts or with other quartz deposits. These gemstones only occur in shades of one color&mdash;light to dark olive green. In the Realms, peridots were frequently used in abjuration spells and magic items that protected against spells and enchantments. A typical specimen had a base value of 500 gp or 50 gp depending on market demand.