The following article about Martin Sheffield appeared in the Thornhill Liberal newspaper in Thornhill, Ontario, Canada on Wed. Oct. 16, 1992. Thornhill business a real gem BY PATRICIA GARCIA Special Martin Sheffield has seen a lot of rocks over the past 13 years. Some were quite memorable, like the 10-carat diamond tiara an older couple brought into his office one day. Others were quite rare, like a gold coin that belonged to a 2,000-year-old bracelet originating from the days of King Herod the Great. Some were downright bizarre, like the one-tonne quartz geode (a stone which has a cavity lined with crystals), which had to be carted to and from his office. Sheffield is the proprietor of Independent Gemmological Services Inc. in Thornhill. Although he's a qualified gemologist and jeweler, Sheffield doesn't buy, sell or make jewelry. He appraises it. He opened his appraisal business in 1979 after deciding the retail jewelry business was neither challenging nor scientific enough for his liking. He's been offering unbiased appraisals ever since, with most of his business originating from word of mouth. Customers range from people insuring their private jewelry to professional jewelers seeking a second opinion on stones they are buying from suppliers. "Some people need an expert opinion to feel good about their purchase and I give them my true and honest opinion," he explained. "I really feel like I'm helping people." WELCOME TO WATCH With clients welcome to watch the process, Sheffield uses the most modern, state-of-the-art equipment available for his appraisals. The process begins with a discussion about the piece, during which it is thoroughly cleaned and identified. The stone is then put under a high-powered microscope to check for its clarity, proportion and finish. "A diamond is the greatest reflector of light," he explained. "The light is internally reflected and bounces out at the top. If the light leaks out at the bottom, the stone is too shallow and is referred to as a fish-eyed diamond." After the examination by microscope, Sheffield uses reflectivity and heat conductance tests to evaluate the stone. A reflectivity machine tests the angle of light going into the stone to confirm it is a real diamond. Since diamonds are good conductors of heat, he measures the speed at which heat passes through the stone. The jewelry is then weighed and valued, using international pricing guides. The data is then fed into a computer which produces appraisal certificates. Sheffield takes a color photo of the stone, which he attaches to the certificate. A microfilm version of the photo is kept on file for later identification. DIAMOND VALUE A diamond's value is affected by the clarity, color, cut and carat-weight, Sheffield says. If the cut is out of proportion, it won't internally reflect light and will lack the benchmark brilliance of a true diamond. "The whiter the diamond, the more expensive it is, but there are no real rules. It's up to the individual taste," he explained. "But don't be alarmed if your seemingly perfect diamond contains a blemish," he added. "This can often serve as a fingerprint to positively identify the stone. And it won't affect the beauty of the diamond one bit." For other gem stones, Sheffield explains it's the hue and color saturation that is most important. He recommends anyone planning to buy a diamond should arm themselves with some knowledge before making that expensive lifetime purchase. Sheffield charges $35 for an average appraisal. For an additional $60, he will include a sketched color-coded map of the diamond, including blemishes as well as a laser gemprint. |