Peridot

It’s time for retail jewelers to begin promoting the birthstone for August—peridot. While in the past it’s taken concentrated effort to sell this lime-green gem, today’s fashion flashback to the ’70s might make this the perfect time for peridot.

But that doesn’t mean it will sell itself. Even when it’s the featured gem, as in a magnificent antique necklace worn at this year’s Academy Awards by actress/model Nastassja Kinski, public recognition is what counts. Kinski’s necklace was noticed twice by People magazine but then disappointingly described—first brushed off as an accent stone, labeled as gold and diamonds with “semiprecious light-green peridots,” then mentioned again as an unnamed gem in a “gorgeous emerald-colored necklace.”

History and name. Peridot’s history begins on a small desert island 50 miles or so off the southeast coast of Egypt in the Red Sea. The name of the island has changed many times over recorded history. Ancient literature calls the island Topazion, sometimes referred to as Topazos, but it now goes by two names—its most recent label, Zabargad, and its immediate past name of St. John’s. “Zabargad” is the Arabic word for peridot, although the English word “peridot” is said to have come from “faridat,” the Arabic word for gem. Coming from “faridat” could account for the American Southwest’s pronunciation of peridot as “PEAR-a-dot,” instead of the more common pronunciation (taken from the French), “PEAR-a-doe.”

The Isle of Zabargad is not a vacation destination, unless you’re a scuba diver. The island measures about three square miles, is littered with mine dumps, and has no vegetation.

According to most gemological texts, peridot was mined on the island beginning in 1500 B.C. and as recently as World War II. But even with that much history, by 1896, peridot was still unheard of in American jewelry. Chrysolites, as they were called, were tiny grains of minerals, most notably found in Arizona, according to Max Bauer, a renowned gemologist of the time. The gem crystals seen in jewelry must have been found in older pieces from “unknown sources, long forgotten,” he wrote. Or maybe the older peridots were still mistakenly identified as topaz, taking the name from Zabargad’s former Topazos name.

But never mind Bauer. Large amounts of peridot were mined from the tiny island, and famous museum and royal gems originated there. Mining has been virtually nonexistent since World War II, mainly because of the island’s location.

Today, there are four major sources of peridot. Large saturated gem crystals come from Burma and—some say more importantly—from Pakistan, with smaller, more moderately colored gems originating in Arizona and New Mexico as well as China. Gem peridot too small to use in jewelry can be found all over the world. Most peridots come from small basaltic volcanoes and lava flows. The green sand beaches of the Hawaiian Islands are fun examples of tiny gem volcanic peridot.

Color. Found typically in medium to light yellowish-green, peridots can come close to being pure and vivid green. They also can fade into brown or yellow primary hues with secondary greenish overtones. (The mineralogical name for peridot is olivine, stemming from peridot’s common “olive” color.) The more saturated and pure the green, the more desirable it is.

Qualities. Peridot can be relatively eye-clean. Especially for the smaller gems, this is expected. Color is most important. One interesting feature of peridot is its strong double refraction, splitting light in two and creating double images of everything inside the gem. This gives all peridot what’s described as a “sleepy” appearance. Double refraction becomes more prominent as the gem becomes larger.

Enhancement. There are no common enhancements known to date. Some of the more highly fractured material may be fracture-filled with oil or epoxies, similar to processed emeralds. However, given the availability of gems with good clarity, most peridots are enhancement free.

Pricing. Peridot is relatively inexpensive. In fact, it’s probably one of the most affordable green gems in the jeweler’s showcase. The larger, more saturated gems from Pakistan have caught the eye of many designers and sometimes end up being carved. The more common lighter colors might be concave faceted, shaped into briolettes, or formed into other styles of beads, all of which drive prices a bit higher. Typical 5-ct. to 10-ct. peridot of fine quality, in normal faceted shapes, can be priced anywhere from $30 per ct. to $60 per ct. For the larger peridots (10 cts. to 20 cts.), prices range from $85 per ct. to $150 per ct. Values start to decrease for gems over 50 cts.

Care and cleaning. Peridots are somewhat durable, but probably can’t take hard wear. Because they have a hardness of just under 7, dust should be washed off before wiping with a soft cloth to prevent scratching and dulling the surface polish.

Bench repair and setting. Peridots are not good at transferring heat, so take precautions to protect them from the torch and anything else that can induce thermal shock—including an ultrasonic cleaner that has been running for a while. Don’t leave a peridot in the ultrasonic for any length of time, otherwise it may get hot and crack at room temperature when removed from the cleaner. Jewelers use borax in jewelry repair, which is then washed off in the ultrasonic cleaner, creating an acidic bath. Placing a peridot into the borax-contaminated ultrasonic bath will etch its surface, requiring refaceting. Steam cleaning is not recommended.

Recommended reading. For more information, see Gem and Crystal Treasures, Peter Bancroft, Mineralogical Record Books (1984), Tucson, Ariz.