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Commonly known as the birthstone of August, Peridot is also the 1st and one of the 16th anniversary stones. It is a readily available, affordable, and attractive yellowish green gemstone that has been used in jewelry since as early as the ancient Egyptians. So how do you even pronounce Peridot? Most jewelers and gemstone collectors say it “pear-eh-doe” because the word does have French origins, however the common American way is “pear-eh-dot”, sounding out a hard “T” at the end of the name. Well guess what! Both are correct and will be found together in most dictionaries.
Apart from its most common yellowish green color, it can range from a lower quality brown-green to an intense pure green, the latter demanding a premium price tag. There is also brown Peridot, though these gems receive little attention. Being the gem variety of the mineral Olivine, Peridot's chemical composition includes iron, the source of its attractive color, and magnesium. This gem is mostly found in basalts, volcanic rocks rich in these two elements. Deposits in these rocks are mostly found as rounded nodules with the crystals inside them, or less often as large crystals lining veins or pockets. Sources for both types are found in the United States, China, Vietnam, Finland, Pakistan, Myanmar (formerly Burma), and the island of Zabargad. It’s believed by geologists that these terrestrial deposits relate to the spreading of the sea floor at divergent oceanic tectonic plates, where these rocks are pushed to the surface. In Myanmar there are examples where these rock deposits have been deformed and incorporated into mountain ranges by later earth movements.
Peridot also has rare extraterrestrial sources. These being stony iron meteorites that survive the fall through Earth’s atmosphere. Peridot-containing meteorites are remnants of the solar system’s birth and known as Pallasite, and therefore the gems extracted are called Pallasitic Peridots. The extreme conditions that these gems endure entering our world mean that most worthy of being cut into quality pieces are usually less than half a carat. Extraterrestrial Peridot was first documented in Siberia, in 1749 by namesake geologist Peter Simon Pallas, and while it was first daring to suggest an interplanetary origin, it is now believed that Pallasite is formed within asteroids with iron-nickel cores and silicate mantles. The extraordinary rarity of this space-formed gem means you will not likely find it in retail jewelry.
The highest quality Peridot will be eye-clean for any inclusions, but will still most likely have them under magnification. The most common inclusions are tiny black spots made of minute mineral crystals. Other inclusions common in Peridot are reflective disk shapes called “lily pads”. There’s a noticeable price drop for light-colored gems with prominent dark inclusions, meaning less color, less clarity, less value in most cases. Fishbone inclusions are common to Peridot originating from Mogok, Myanmar, and there was recently a brown Peridot found in southeast Vietnam that revealed script-like inclusions of Serpentine.
Peridot’s look is also characterized by is high birefringence or double refraction, causing a doubling effect on the appearance of the edges of the lower facets seen through the top table facet of a cut gem. This is an easy distinguishing quality of Peridot against its imitations. Rare visual properties for Peridot to have are chatoyancy (cat’s eye) and asterism (star), and interestingly, all known star Peridots to date have been of Burmese origin.
Peridot can be found in all types of cuts and sizes, though expect the affordability to do down in gems over 10x8mm. It is commonly untreated, but can be heat treated to improve color or clarity as a normal practice. As for grading Peridot, individual companies may create their own quality scales to denote the range of their stones’ values, but no standard quality-grading scale exists for this gem. So what may be a AAA grade for one seller, may be AA quality for another. There is also no premium placed on the origin of Peridot, excepting that of the island of Zabargad due to its historical importance and because it is not currently commercially producing gems.
Peridot has always been associated with light and the Egyptians called it the “gem of the Sun” believing it protected wearers from “terrors of the night”. It is also the zodiac gemstone for Libra, and is reputed to bolster their self-confidence by freeing the mind of negative thoughts. It is also known as the stone of compassion, bringing peace to relationships by balancing emotions and minds. Legend says that being set in gold will bring out the full powers of Peridot, and according to Pliny the Elder, its most potent dispelling came from being worn on the right arm. Though Egyptians believed a strand of them tied to the left arm with donkey’s hair would ward off evil spirits.
Peridot is rated “fair” for everyday wear with care. Please avoid exposure to heat, sudden temperature changes, and contact with chemicals, especially acids. To clean, gently scrub with a soft toothbrush and a solution of mild dish soap and warm water.
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Photo Citations
Thread-like inclusions of serpentine resembling an ancient text. Photomicrograph by Le Ngoc Nang; field of view 2.50 mm.
The fishbone-like inclusion in the Burmese peridot. Photomicrograph by Shu-Hong Lin; field of view 1.32 mm.
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