Chemical Formula (Mg,Fe)2SiO4
Color Green, Yellow
Hardness 6.5 – 7
Crystal System Orthorhombic
Refractive Index 2.63 – 2.65
SG 1.54 – 1.55
Double Refraction .009
Cleavage 2,1 ; 3,1
Mineral Class Olivine
The history of Peridot is intrinsically tied to the tiny Egyptian island of St. John (Zabargad) in the Red Sea, which was the one of the only ancient sources of gem Peridot. This deposit has been totally exhausted, though fairly significant deposits have since been discovered, especially since the 1990′s.
Findings of large transparent Peridot from Burma (Myanmar), China, Afghanistan, and especially Pakistan have provided a new quality of Peridot unlike anything else previously discovered, with large, nearly flawless crystals that are well-suited for gemstones. The new discoveries are responsible for a reawakened interest in this gemstone. However, the most significant producer of gem Peridot remains the San Carlos Reservation of Arizona.
Although many Peridot gemstones, especially older ones, have cloudy or milky inclusions, the more recent gemstones on the market have few flaws and can be of exceptional quality. Though pretty and popular, Peridot is not a very durable gemstone. It has a lower hardness than many gemstones and is more prone to scratches, and has a tendency to occasionally burst under great stress. Peridot also cannot stand intense heat or rapid temperature changes. Peridot can also chip if banged hard, and should never be steam cleaned or cleaned with ultrasonics.
Much gem Peridot comes from igneous environments. These gems are formed deep within the mantle of the earth, and are brought the the surface by volcanic activity. Peridot is also found in certain types of meteorites, though these forms of Peridot are too rare and usually too small to be used as gemstones.
Peridot is both a day stone and a night stone, keeping its shining color even under artificial lighting. For this reason, it is sometimes called “Evening Emerald”. Although Peridot can be pronounced both with and without the “t” at the end, most professionals in the gem trade pronounce the “t”.
Peridot gems are usually small, though large flawless stones are occasionally cut. Peridot is a popular and affordable gemstone and is faceted into many cuts, and used in all forms of jewelry, especially rings, earrings, necklaces, and bracelets. Tumbled Peridot beads and cabochons are also fashioned in bracelets and necklaces.
Peridot is the birthstone of August.
OlivineThe color of Peridot gemstones are natural and not enhanced. Synthetic Peridot is produced, but this is not commonly done.Although the mineral Olivine is fairly common, the gem form of Peridot is more limited. Egypt was the ancient source of Peridot, but now the main sources are in Pakistan, Burma, Afghanistan, China, Vietnam, Ethiopia, and the United States (Arizona). Hawaii on occasion produces some Peridot large enough to be cut into gemstones, but most “Hawaiin Peridot” is not authentic from Hawaii.The color of Peridot can be similar to Tourmaline, Demantoid, and Green Amethyst. The color of Emerald is usually a deeper green tone.
Prehnite gemstones are usually light green in color, with a whitish hue or yellowish tinge. Deep green gemstones are not common. Prehnite gemstones often appear cloudy or velvety, and rarely fully transparent. They may also contain colors zones of lighter and darker green.
Peridot TREATMENTS AND ENHANCEMENTS