About Peridot
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. Different localities produce different shades of green.
Olivine, of which peridot is a type, is a common mineral found in rocks that are rich in magnesium and iron and it is often found in lavas and in rock fragments which lavas carry to the surface; but gem quality peridot occurs in only a fraction of these settings. Peridots can also be found in meteorites. Peridot has a hardness of 6.5 to 7 on the Mohs scale.