Peridot Gemstone Information

Peridot is a gem-quality from the range of olivine. It is derived from the forsterite-fayalite mineral series. Peridot is considered to be a dichromatic gem that means the color comes from the basic chemical composition of the mineral itself and not from minor traces of impurities. In fact peridot is only available in green color. Even though the shades of green may vary from light yellowish to dark brownish-green.

The history of Peridot is intrinsically tied to the tiny Egyptian island of St. John (Zabargad) in the Red Sea, which was tend to be the only ancient sources of gem Peridot. In fact Peridot is both a day and a night stone, making the shining color even under artificial lighting. Due to this reason, it is sometimes called "Evening Emerald".

The name 'peridot' actually came from the Arabic word for gem - 'faridat'. Sometimes it is referred as 'the poor man's emerald' or as 'chrysolite', a word derived from the Greek word 'goldstone'. It is one of the oldest known gemstones, with date as early as 1500 B.C. Historically, the volcanic island of Zabargad (St. John) in the Red Sea, east of Egypt contains the most important deposit that was exploited for over 3500 years. At present, the finest quality peridot comes from Mogok in Burma, still, the Pakistani peridot is now highly regarded as well. Different other important sources available are in Arizona, China and Vietnam. The gemstone has also been discovered in fallen meteors and it has also been discovered on Mars and the moon in olivine form. Peridot is the birthstone of August.

Recognise - Peridot is an iron magnesium silicate and the power of color depends on the amount of iron it carries. However we could find few traces of nickel and chromium present. Peridot is not that hard and it has no resistance to acid. Very rare, peridot seems to be known to form with cat's eye chatoyancy (asterism) in the form of four ray stars. Many times Peridot is confused with similar colored gems, but its strong double refraction is frequently a very distinguishing trait. Stones that are thick the doubling of lower facet edges is seen by seeing down though the table without the need for magnification.

Availability - Most gemstones are formed in earth's crust, however peridot is formed much deeper in the mantle region. The formation of Peridot crystals is in magma from the upper mantle and are brought to the surface by tectonic or volcanic activity where they are found in extrusive igneous rocks. Historically, Zabargad (St. John), the volcanic island in the Red Sea was the location of the most important deposit.

Currently, the important deposits are found in Pakistan (the Pakistan-Afghanistan border region and in the Kashmir region). Beautiful material is also found in upper Myanmar (Burma) and Vietnam. Other deposits are found in Brazil (Minas Gerais), Australia (Queensland), China, United States (Arizona and Hawaii), Kenya, Mexico, Norway (north of Bergen), Tanzania, South Africa and Sri Lanka. Lately, China tends to become the largest producers of peridot.

Usages - Peridot gems are usually small, though large flawless stones are rarely cut. Peridot is a common as well as affordable gemstone. It is faceted into many cuts, and is used in all forms of jewelry, especially rings, necklaces, earrings, and bracelets. Beads of tumbled Peridot beads and cabochons are also fashioned in bracelets and necklaces. Peridot is a stone of lightness and beauty. Peridot should be used by spiritual or clear-minded persons.

Buying Guide

Color - Peridot is among the few gemstones that is available in a single color. The level of iron content in the gemstone is responsible for the depth of green. The color of Peridot vary from yellow-green and olive to brownish green and gives an excellent look in natural daylight. In artificial light the vivid green color does not change. The best colored peridot has an iron percentage of less than 15% and naturally some trace elements of nickel and chromium are added, which contribute to its color. A deep and strong green colored peridot is considered the most demanding and the most valuable.

Clarity and Lustre - Peridot is available with excellent transparency. Eye-clean specimens are abundant, however larger stones may appear slightly cloudy because of the presence of inclusions and impurities. When cut and polished, peridot consist of an attractive, vitreous luster and greasy.

Cut and Shape - Peridot is faceted naturally because of its excellent transparency. Table along with step cuts are very famous, as well as unconventional checkerboards. Peridot can be found in various shapes that includes fancies and traditional ovals, rounds, emeralds (octagons) and cushions.

Treatment - Peridot is not treated typically or enhanced in any sort. However, there are reports of metal-foiled peridot that helps to increase stability along with the paler stones that may be coated with green foil to improve the color. Imitation peridot are also found.

Gemological Characteristics:

Chemical Formula	(Mg,Fe)2SiO4 Magnesium iron silicate
Crystal Structure	Orthorhombic; vertically striated , short compact prisms,
Color	olive-green, Yellow-green, brownish
Hardness	6.5 to 7
Refractive Index	1.650 to 1.703
Density	3.28 to 3.48
Cleavage	Indistinct
Transparency	Transparent
Double Refraction or Birefringence	0.036 to 0.038
Lustre	Vitreous, greasy
Fluorescence	None
SG	1.54 - 1.55
Mineral Class	Olivine

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