Semi Precious Peridot StoneHardness : 6.5 - 7.0 Appearance :Olive green to yellowish green. The darker green is known as peridot, the yellower type chrysolite. Peridot and sardonyx are the birthstones of the month of August. Enhancements :Peridot is rarely treated with colorless oil, wax, natural and synthetic unhardened resins into voids to improve appearance. Surface fractures are rarely filled with a colorless hardened substance.