Peridot (/ˈpɛrɪdɒt/ or /ˈpɛrɪdoʊ/) is gem-quality olivine, which is a silicate mineral with the formula of (Mg, Fe)₂SiO₄. As peridot is the magnesium-rich variety of olivine (forsterite), the formula approaches Mg₂SiO₄.

Peridot is one of the few gemstones that occur in only one color: an olive-green. The intensity and tint of the green, however, depends on the percentage of iron that is contained in the crystal structure, so the color of individual peridot gems can vary from yellow, to olive, to brownish-green. In rare cases, peridot may occur in a medium-dark toned, visually pure green with no secondary yellow hue or brown mask.^[3]