The Emerald Test

A couple of long-held “facts” about emeralds are being called into question:

Fact #1: All emeralds are green.

Fact #2: Emeralds are fragile. These two bits of conventional wisdom have been challenged by some recent developments in marketing and enhancements:

Point #1: Most consumers would rather buy a “pink emerald” than a “morganite.”

Point #2: At least one jeweler recommends cleaning emeralds in an ultrasonic cleaner.

Here’s a closer look at the issues.

The color of emerald. According to the definition in Peter Read’s Dictionary of Gemmology, emerald, listed under beryl varieties, is bluish-green to medium yellowish-green. The Gemological Institute of America agrees, with some slight differences: According to its colored-stones course, emeralds occur in very strong bluish-green to green to very slightly yellowish-green. The most desired emeralds have strong to vivid saturation, are medium to dark in tone, and of bluish-green to green hue.

But not all green beryl is called “emerald.” If the color is considered too weak, pale, or desaturated, it’s called “green beryl.” But how an appraiser arrives at this decision is very subjective.

Science lessons. Beryl is a beryllium-aluminum silicate. In its purest form, it’s a colorless mineral called goshenite. Green emerald is colored by trace amounts of chromium and/or vanadium and iron. Generally, the greater the amount of chromium or vanadium, the more saturated the green color. When there’s more iron, the emerald has more blue; when there’s less iron, the emerald is a more pure green.

Red and pink beryls, colored by manganese with a slight amount of chromium, are called bixbite and morganite, respectively. But bixbite is hardly a common name in the trade—it’s marketed as “red emerald.” Found in the Wah Wah Mountains of Utah, red beryl has been a hard sell.

Ray Zajicek of Equatorian Imports in Dallas, one of the better-known wholesale dealers specializing in the rare reds, has been criticized by purists who say emeralds are only green. Others disagree with this notion and point to corundum and the definition of sapphire. Read’s dictionary describes sapphire as colorless, blue, pink, orange, yellow, green, and purple. It has long been standard in the trade that “sapphire” used alone denotes a blue gem. All other colors of sapphire are preceded by the word “fancy” or the specific hue. “Red emerald,” therefore, is as valid a term as yellow sapphire, green sapphire, purple sapphire, etc.

But red emerald isn’t the only upstart. There’s also pink emerald. “Many feel the ‘pink emerald’ name just isn’t appropriate,” states the Pink Emerald Company in North Carolina, host of the Web site.

Pink emerald? Isn’t that morganite? According to Ted Hens of the Pink Emerald Company, pink emerald is actually rosterite, found years before George Kunz named it after his employer, J.P. Morgan. (Kunz was also an advisor for Tiffany at that time.)

According to, “In the mineral trade, pink emerald is known by the mineral names: pink beryllium-aluminum silicate, pink beryl, rosterite, vorobievite, worobieffite, and morganite.” The Pink Emerald Company says that list represents the chronological order in which the mineral was discovered.

Aquamarine, another beryl, has its own following, so don’t expect to see “blue emerald” at the next trade show. But Hens says he wouldn’t be surprised to see “golden emerald”—which falls more trippingly from the tongue than “heliodor”—someday soon.

The durability of emerald. Are emeralds fragile? “They’ll explode from thermal shock,” says Ronda Coryell, jewelry bench expert at the Revere Academy of Jewelry Arts in San Francisco. “Ultrasonic vibrations will cause fractures and fissures to become larger.” Coryell also says the oil that’s often used to treat emeralds makes them poor candidates for ultrasonic or steam cleaning, which use heat and, in the case of ultrasonic cleaning, chemicals.

“Emeralds are softer, abrade easily, and should never be heated,” Coryell adds. “We suggest you clean them in lukewarm water only. This is especially true if it’s someone else’s jewelry. It’s your responsibility as a jeweler not to take the chance.”

Joseph Gad, a longtime emerald wholesaler in New York City, agrees: “You never put an emerald in the ultrasonic.”

But Arthur Groom, an emerald wholesaler and retail jeweler, disagrees. He thinks emerald has gotten a bad rap because jewelers and consumers don’t know what’s really inside the gem. Fractures and fissures are commonly hidden by fillers, Groom says, so when an ultrasonic or steam cleaner removes the filler, the now-obvious fissure leaves the impression that new damage has occurred. Hidden inclusions in corners reveal themselves only after a setter breaks the corner.

Tom Chatham of Chatham Created Gems agrees with Groom’s assessment but says, “There is another problem with emerald. [There was] one my father and I worked on for three years back in the 1970s. We didn’t prove our theories, but we fixed the problem of cracking. Sometime in the mid-1970s we began to have trouble cutting our stones. Nice, gemmy, clean rough would develop gletzes [feathers/fissures] during the cutting process. Some crystals developed gletzes sitting in a display, with no outside help. We had a problem.

“Emerald grows twice as fast along the C axis as it does on the A axis,” Chatham explains. “That’s why the crystals are always longer than wide. This causes stress within the crystal structure between the bonds of the silica. We adjusted our saturation of silica and got rid of the problem—after about three years of guessing. Whether it was truly the silica bond, or the silica affected other bonds, we were not sure, but we fixed that problem, all the while making emerald every time. It would be fair to conclude that this problem exists in nature, maybe even to a greater degree. So grandma may have been telling the truth when she said, ‘The stone just cracked in two sitting on the nightstand!’ “

“I’ve broken an emerald while setting it,” says Gary Bowersox of GeoVision, Gems from Afghanistan, located in Hawaii. But he was just learning. “I pulled on opposing prongs—bad setting technique.” As for emerald’s durability under normal conditions, Bowersox says, “I tell customers emerald is a hard substance.” (Emerald ranks 8-8.5 on the Mohs scale.) “It’s like cement,” says Bowersox. “Emerald is hard, but when you have feathers or cracks, the structure is weakened. Therefore, the better-quality emeralds are less fragile.”

Jewelers resist emeralds because they are supposedly easy to fracture, says Groom, who claims it’s not true. “It wasn’t that fractures can happen, but rather that the enhancement probably disappeared [and the fracture was revealed],” says Groom. “We never had an enhancement that was stable—that was the problem.”

Gad is concerned that a filler might inadvertently be removed by ultrasonic or steam cleaning. Nevertheless, he advises using a filler that can be removed at the client’s request. He maintains that cedarwood oil, which he calls a “more natural product,” is best. “In Colombia, it’s accepted and commonly preferred to use cedarwood oil,” Gad says. “It has the closest refractive index to emerald and can be removed whenever you want.”

According to Gad, it’s important to use a substance that’s organic. “When you apply an epoxy or resin, it brings down the value,” he says. “If I gave [customers] a resin, they’d be very upset.” Others say resin changes the properties of the stone.

Groom’s response to the filler problem was to develop his own, which he calls ExCel. He provides a written lifetime guarantee with every emerald he sells: If the filler ever discolors, fades, dissolves, deteriorates, or washes out, Groom will re-enhance the emerald or replace it with an enhanced stone of equal or greater value—free of charge. In fact, he’s so confident of the stability of his enhancement and the stability of the emerald itself that he recommends cleaning emeralds with ultrasonic—and steam!

This doesn’t surprise Gad. “Of course,” he says. “It’s a glue—it’s an epoxy resin.”

Zajicek, who has been in the Colombian green emerald business since 1968, is familiar with the usual emerald enhancements, but he prefers ExCel. According to Zajicek’s Web site,, “Owners of our merchandise enjoy the convenience of ultrasonic cleaning for their emeralds and the absence of need for ‘re-oiling.’ “

As the controversies surrounding emerald enhancements and terminology evolve, JCK will continue to monitor the latest developments.

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