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Peridot Science

Peridots are transparent with a distinct oily luster. Peridot’s color can be described as yellow-green, green with a golden tone, olive or bottle green, deep chartreuse, or simply a brilliant light green. The proportion of iron present causes the shade and depth of the green of a peridot stone; the deeper the green, the smaller the amount of iron present. Peridot is one of a few gems that are not routinely treated. While it is not particularly brilliant (peridots have moderate to high brilliance), the richness of its color can be exceptional and is completely natural. Because of its rarity, peridot is not usually seen in its deeper pure green colors however newly discovered sources may change this. New sources include Arizona, Mexico, Oregon, Norway, Pakistan, Russia and Sri Lanka.

The best and safest way for you to clean your peridot, is with warm, soapy water. You should take special care of your peridot to ensure that it does not come in contact with drastic temperature changes, which can damage the stone. You should also protect your stone from scratches and sharp blows and avoid any contact with chemicals. Peridots should not be cleaned in ultrasonic or steam cleaners.

As with all fine gem crystals, small crystals are relatively common and larger stones seldom occur free of flaws. The larger the crystals are, the easier they flaw, from such seismic disturbances as earthquakes and volcanic eruptions. The ways in which the stones are cut and faceted are designed to eliminate these imperfections. It is not uncommon for a 20-carat stone in the rough to only yield three or four gems of only one-half to three carats each. Because large stones have become so rare, the green for which this gem has for centuries been praised, is seldom seen these days. This saturate green was so highly prized, that one of antiquities favorite compliments to peridot, was to mistake it for emerald.

Peridot was formed early in the solidification of the Earth. As the earth’s magma slowly cooled to form igneous rock, peridot was born. Parts of the magma which cooled particularly slowly created large and clear specimens of peridot. These rich deposits are located in Egypt, and in Burma as well as surrounding areas.

Peridot has been part of the lava and magma spewed forth from volcanic eruptions. In Hawaii, the black basalt rock and beaches are studded with millions of tiny peridot grains. Although most of the peridot on Hawaii is either too small to use, or is locked up in very hard rock and cannot be mined, some pieces of Hawaiian peridot have led to jewelry quality stones.

Peridot is also an important component of kimberlite, which is the mineral matrix in which diamonds are found. Kimberlite deposits are rich in microscopic grains of peridot. In South Africa, the ground around several diamond mines is blue-green in color due to the saturation of tiny peridots.

Peridot is not only born of fire here on earth, but it has also arrived to Earth from outer space. Although many different gems can be found in meteorites that have fallen to earth, peridot is the only one that is found in large enough sized to make jewelry from. In 1749, a meteorite landed in a desolate area of Siberia. It was found to contain many pieces of peridot crystals large enough to be set into jewelry.

Most of the peridot mined today comes from China, Pakistan, and Arizona and the gems that are found are mostly under 3 carats. Two of the finest peridot collections in the world can be found at the Field Museum in Chicago, and the Museum of Natural History in New York.

Peridot is a relatively soft stone, rating a 6.5 to 7 on the hardness scale, making it a little softer than amethyst or emerald. Peridot should be spared rugged wearing if mounted in rings. The stone is also highly sensitive to rapid temperature changes. Peridots can also lose their polish if they come in contact with commonly used hydrochloric of sulfuric acid.

Peridot occurs in a limited number of locations. It occurs in silica-poor igneous rocks, such as basalts, gabbro, troctolite, and peridotite. Some peridot is found in volcanic bombs, while some are found embedded in meteorites. These stones are not usually of gem quality but a few have been faceted and mounted in jewelry settings. As with many precious gems, peridot also occurs in small, worn-down, pebble-sized specimens, weathered by tens of thousands of years of erosion in gem stone gravels. Peridot can be found in the Canary Islands, China, Brazil, Norway, Hawaii, Australia, Pakistan and South Africa. Burma produces some good peridots, however these tend to be a darker shade of green. Brazil, as well as Arizona and New Mexico, also provide some fine, though usually small gemstones.