Professional Jeweler Archive: K-9 Gemology

February 2001

Gemstones & Pearls/News

K-9 Gemology

A pooch with a refined snoot can make gemological separations that still confound sophisticated laboratories

For Tara, a Belgian Malinois, Gemology 101 consists of one thing. She must know how to single out the unique aroma exuded by the epoxy resins sometimes used to enhance the clarity of emeralds.

Sniffing for epoxies is a skill she’s been taught by her owner, Mark Rispoli, a trainer at Makor K-9 in Napa, CA. In a controlled experiment, Tara is confronted by a row of jars containing emeralds. One jar contains an emerald whose network of minute surface-reaching fissures is laced with an epoxy resin. All other jars contain emeralds enhanced with cedarwood oil or another substance. Her job is to get a whiff of, and identify, the epoxy resin-enhanced emerald. About four seconds later, Tara pauses by one of the jars, sits down and emits a knowing “woof.”

She is spot-on in her assessment. Her payment for the successful completion of her gemological chore is a chance to play with a rubber toy.

A Flying Dog

Most gemological labs in the world find it hard to make the separation at all. Those that do require expensive and sophisticated gemological equipment, such as Raman spectrophotometers, and lots of time to perform tests. And when it comes to the business aspect, labs ask for far greater remuneration than a chance to frolic with a rubber toy and receive a pat on the head.

“What’s more, the gem labs are not always at the source where you need them,” says Andy Rendle of EmeraldStone Inc., whose offices are in Victoria, BC, Canada, and Bogota, Colombia. But if you buy emeralds in the Colombian open market, like EmeraldStone does, Rendle says, it’s crucial to know the identity of an enhancement in an emerald offered for sale. So Tara has accumulated quite a nice packet of frequent flier miles on her trips to Bogota.

Defending Nature

Rendle has no objections to the many enhancement fillers that exist, including epoxy resins, but says his company is angling for a competitive edge. “We want to increase the quality of emeralds without treatments.”

EmeraldStone prefers no enhancements or, at most, enhancement with cedarwood oil. “My belief is that between wholesale and the consumer, everything in an emerald must be seen,” says Rendle. But what’s in an emerald isn’t always disclosed in the marketplace, so Rendle wants to be able to single out those filled with epoxy resins. If Tara sniffs out epoxy resins in a parcel offered for sale, EmeraldStone passes on the entire parcel.

Finding unenhanced or, at most, cedarwood oil-enhanced emeralds has been adopted by the parent company, Rio Verde Holdings Ltd. of Canada, an exploration and mining concern that has teamed up with EmeraldStone Inc. to market Colombian emeralds. The Rio Verde Group is prospecting in various emerald zones and plans to mine for emeralds without using the glucose-based dynamites routinely used in emerald mining. “The dynamite wrecks the integrity of the rocks and the emerald crystals,” says Rendle. “Our mechanized mining, adapted from old coal-mining machines, removes just the surface of a wall with scoop trams. It’s much less damaging to emerald crystals. Then the need to enhance them drops considerably.”

The Nose Knows

For now, marketing is focused on emeralds in the market already. Tara and several other “gemhounds,” including her daughter, Diva, are the testers.

Rendle says a dog’s olorometro (Spanish slang for “odor meter”) is so refined it can detect odors in parts-per-million. Dogs have long been used to detect deadly gases in tunnels, hidden drugs, propellants used in arsons, bomb-making supplies or, more positively, to locate victims in rubble or avalanches.

“We’re not replacing gemologists,” says Rendle. “We use the dogs as a complement to the optical aspects used by gemologists.” EmeraldStone has worked with scientists on gas chromatography projects, but found that any small change in a polymer recipe – or if the surface of an emerald was polymerized – meant chromatography mapping had to start from scratch. All the while, EmeraldStone used Makor K-9 dogs as security. Rispoli suggested the dogs be used to sniff out epoxy resin-enhanced emeralds.

If a dog is already scent-trained, it can take as little as five minutes for it to learn to recognize a particular smell, which is about how long it took for EmeraldStone to realize Tara’s potential as a gemologist.

There are some problems, Rendle admits. For example, a stone with epoxy resin rubbing against a natural emerald could cause a false reading, much as air turbulence causing the vapors from one jar to move toward another jar could. Tara’s nose may be too refined.

“But we have done a lot of testing,” says Rendle. “We are refining how we do our tests and are amazed at how consistently Tara can discriminate odors. We are seeing a 95% success rate. We’ve performed separate testing for oils, acetone and various plastics, and already trained dogs can easily be retrained to sniff out a particular odor.”

Tara, step forward for your G.S. (Graduate Schnozzle).

EmeraldStone Inc., Vancouver, BC, Canada; (800) 363-7253, or

– Robert Weldon, G.G.

Is this emerald enhanced with an epoxy resin?

Ask Tara.

Copyright © 2001 by Bond Communications