Last updateTue, 11 Feb 2020 10pm

The Retailer’s Perspective: You can’t tell the difference

When I started in this industry in September of 1978, quartz watches had just hit the market. I worked in the jewelry warehouse of a catalog showroom called Best Products in Dallas, TX, and quartz watches were literally flying off the shelves. According to the industry vets at the time, this was the first real major change to hit the industry in decades. Now it seems there’s a new major change happening every month or two. Today, we’re going to talk about the most recent game changer; lab-grown diamonds.

As it turns out, they’ve been around a lot longer than we thought. There’s a lot of surprised folks out there that swore they’d never sell anything except a genuine diamond. As it turns out, lab-grown diamonds have been unscrupulously peppering the melee supply chain for some time, and none of us knew it was happening. That’s not good, not good at all.

For starters, let’s get an understanding of what is a ‘lab-grown’ diamond? A lab-grown diamond is actually a synthetic diamond. A synthetic gemstone, by definition, is a man-made gemstone that matches its natural counterpart, chemically, physically and optically, within narrow limits. Diamonds are a rare, single element gemstone (carbon), listed on the periodic table of elements as ‘C’.

A diamond is pure carbon, with no other elements present, aside from some trace elements picked up during its 63 million year trek to the surface. A synthetic diamond is a single element gemstone that is listed on the periodic table as ‘C’. In other words, they are identical! In most jewelry store environments, you can’t tell the difference between the two. If that doesn’t scare the bejesus out of you, I don’t know what will.

I’ve been a gemologist since 1983, and have sold, graded and appraised tens of thousands of diamonds - all natural and genuine - I hope! Since 1983, I haven’t needed outside help from a gem lab to tell me if a diamond is an SI1 or an I1. That’s what my gemological certification is for. But now we all need help to tell us if it’s a natural or a synthetic. After that, most gemologists are good-to-go on the rest of the grading. So, who do you turn to to make that genuine/synthetic determination? For the answer, I interviewed three prominent gem labs that are in the business of making that determination for you. I hope this helps.

Stone Group Laboratories (SGL), Jefferson City, Missouri

The thing I liked the most about this lab is all of their reports are signed by Bear and Cara Williams, husband and wife FGA’s. I like knowing who I’m trusting to form my opinion. If you’re not familiar, FGA stands for Fellow of the Gemological Association, and it is the highest level of gemological training and certification available in the world; and SGL has two FGA’s on staff! While colored gemstones have always been their primary focus, they are seeing an increased demand for diamond verification as treatments and synthetics become a larger part of the market and harder to detect.

SGL only offers reports that can be backed up by science. They don’t offer grading, pricing, or color opinions; all of which are open to subjective opinions. They only offer the facts on which jewelers can base their decisions.

SGL will examine your stone in their state-of-the-art laboratory, and will tell you the basics; natural/synthetic, if the color is natural or enhanced, and any treatments the diamond may have undergone. Their service costs $30 per diamond for a verbal report, and takes less than a week; written reports with a photo cost $60 per stone and takes up to 10 days. If, like me, you’ve spent the thousands and thousands of dollars to earn your gemological certification, this is really the only outside help I need. As a long-time gemologist, I can take it from there.

You can contact them at: Stone Group Laboratories, LLC, This email address is being protected from spambots. You need JavaScript enabled to view it., www.stonegrouplabs.com, 573-635-0627

Professional Gem Sciences Laboratory (PGSL), Chicago

This lab was founded in 1980 and came highly recommended. They offer a full gemological lab experience, and take it a step further and also offer complete appraisal services. Your diamond will be screened upon receipt for natural vs. synthetic. For $15 you can get that information verbally and stop right there if you want. If you choose to go further, for around $100, you’ll get a complete diamond report, including a full appraisal. All of this takes 2-4 business days. PGSL is staffed by a number of GG’s, and their senior gemologist is also an FGA.

PGSL also offers breakout gemstone sorting in bulk that separates natural gems from man-made stones. In today’s environment, you really don’t know what you’ve got and probably need to get it all tested. You can contact them at: PGS Laboratory, 5 S. Wabash Avenue, Suite 315, Chicago, IL 60603, 312-920-1541, www.pgslaboratory.com


GCAL has two major distinctions from other labs around the world. First, GCAL takes responsibility for its work with an exclusive 4Cs Guarantee to the consumer. Second, it is the only ISO 17025 Accredited Forensic Gems and Jewelry Laboratory in the world. There are only three gem labs in the world that are ISO 17025 Accredited. In 2014, GCAL became the only gem lab in the world to earn the ISO 17025 Forensic Accreditation. This certification means their grading methods and equipment is tested, audited, and calibrated, and complies with very rigid standards. This assures you that the testing that you are paying for, and relying upon, is as accurate as it can be.

With GCAL, every diamond that comes in for a grading report gets a Gemprint® “fingerprint” and a laser inscription on the girdle. Lab-grown diamonds receive two laser inscriptions - one stating ‘Lab Grown’ and the second with the GCAL Certificate Number. The full report, with high resolution imaging, Gemprint®, light performance, guaranteed grading, and inscription, runs about $100 for a 1 carat diamond, with a 2-3 day turnaround for a single stone. Parcels take about a week.

GCAL will first analyze your diamond to determine if it’s natural or lab grown. From there, it will go through a number of steps, including weights and measures, Gemprint®, high resolution imaging, light performance, and treatment/enhancement detection. Then, a number of senior gemologists will make the various grading decisions utilizing blind consensus grading for the rest of the grading process. GCAL has one location, one standard, and all testing is done in New York City. You can contact GCAL at: 212-869-8985, This email address is being protected from spambots. You need JavaScript enabled to view it., www.GCALUSA.com

With any lab, the most important thing to me is who is doing the actual testing that I’m going to rely upon? I like knowing that seasoned gemologists are making these calls, because it’s my butt on the line at the retail sales counter. I like being positive about what I’m selling and signing MY name too.

Since lab-grown diamonds are so new, the standard diamond/moissanite multi testing equipment you have just won’t cut it anymore. So, what sort of equipment should you have in your store to help safeguard you against this new situation? For the answer to that question, I contacted Gabriel Sep with Sep Tools of Chicago.

In a nutshell, there are two price points to consider; $550 and $6,600. For $550, he recommends three different units, The SmartPro, the Gemlogis, and the Presidium II. They will alert you by indicating a red light result for possible synthetic, blue light for natural earth mined diamond. These devices use UV light technology which is different from your current tester which utilizes thermal conductivity. The only precaution is that you must pre-test the gemstone and be positive that it is a diamond. If you use these testers with Moissanite or CZ, they can give a false reading as either a natural or a synthetic diamond. It can also alter the calibration and you will have to send it back for recalibration. But, the Diamond/Moissanite tester you already have is capable of making that distinction.

These machines are limited to testing a single stone at a time, which for most retail stores, is acceptable.

If you buy in bulk, like estate buyers and pawn shops, you need a different piece of equipment. That’s where you jump up to the $6,600 Yehuda Sherlock Holmes 2.0, which is the most popular device in its class. This piece of equipment will test large parcels and mounted goods at the same time. It will also separate Moissanite and CZ during its screening, so it eliminates the pre-test required by the testers above. Log on to SEPTools.com, click on gemology tools, and scroll down to the CVD/HPHT section and you can find more information. If you need more help, call Gabriel at 312-541-4554.

And, just to be clear, let me reiterate; You Can’t Tell the Difference.

Who’s going to come see me at the Bench Jewelers Laser and Technology Conference in Nashville, TN on August 16 and 17?

Chuck is the owner of Anthony Jewelers in Nashville, TN. Chuck also owns CMK Co., a wholesale trade shop that specializes in custom jewelry and repair services to the jewelry industry nationwide. If you would like to contact Chuck or need a speaker or instructor for your next conference/event he can be reached at 615-354-6361, www.CMKcompany.com or send e-mail to This email address is being protected from spambots. You need JavaScript enabled to view it..