There are several ways to determine the authenticity of a diamond, including tests that can be done at home. These tests are mostly for checking the physical qualities of a gem—the sparkle, scratch, drop, and clarity tests, to name a few. But arguably the quickest and most definitive way to check if a gemstone is genuine or fake is by using a diamond tester.
What is a diamond tester?
Real diamonds have unique chemical and physical structures that differentiate them from other gemstones, kind of like DNA. As such, the way diamonds conduct heat and electricity is different from that of moissanite, cubic zirconia, colorless sapphire or colorless topaz, and other diamond simulants that, to the untrained eye, could pass for the real thing.
A diamond tester is a portable device with LED display, light or sound indicators, and a small needle-like probe at the tip. When the probe is placed on the gemstone that’s being tested, the device typically emits a sound and shows the result on its display, in a matter of seconds.
Diamond testers can tell if the gem is real or fake by measuring its thermal or electrical properties—i.e., the speed at which heat or electricity travels through the stone—noting that different gemstones tolerate different amounts of heat, pressure, or stress.
Where can you find reliable diamond testers?
When canvassing the market for diamonds, opt for stones with legitimate certification from the world's top gemstone institutions: Gemological Institute Of America (GIA), American Gem Society (AGI), and International Gemological Institute (IGI). A certificate from a reliable lab tells you if the seller's claims about the diamond you're buying are true.
As for diamond testers, there are thousands of gemological instrument manufacturers all over the world, making it difficult to decide which brand to trust. When vetting the instruments and technology offered by these companies, it’s only logical to assume that the industry pioneers would have an edge.
One such industry forerunner is Presidium Instruments Pte Ltd—the world’s first company to launch groundbreaking gemological instruments. Incorporated in 1979, Presidium is the global leader in gemological instruments that test and measure diamonds and gemstones.
Why choose Presidium for diamond testers?
In our more than 40 years of experience, Presidium has built the expertise and authority to guarantee the reliability of our technology. To speak for itself, here’s a lineup of Presidium’s industry-trusted products:
The ARI by Presidium is a PRESIDIUM DIAMOND VERIFICATION INSTRUMENT®, which is a registered trademark of Presidium Instruments Pte Ltd. It distinguishes colorless diamonds from CVD/HPHT lab-grown diamonds or moissanites from D to J color, for loose and mounted stones as small as 0.02ct. It works well with the Presidium Diamond Mate Tester (PDMT-A) to easily identify natural diamonds, lab-grown diamonds, moissanite, and diamond simulants.
The Presidium Diamond Mate Tester (PDMT) boasts of the thinnest probe tip size, which is 0.6mm. It is the industry’s tiniest probe tip to date, which means the PDMT can be used on diamonds as small as 0.02ct. Test results are instantly indicated by an LED light and a continuous audible beep. The PDMT instantly verifies the authenticity of diamonds based on their thermal properties.
The PDMT-A is a complementary product to ARI, for further distinguishing diamond simulants such as colorless sapphire and cubic zirconia from unknown colorless stones. As a first step, users can test an unknown colorless stone using the PDMT-A. Upon a positive "Diamond" reading, users can then use ARI to test if the stone is a natural diamond, potential lab-grown CVD/HPHT diamond, or moissanite.
The Presidium Multi Tester III (PMUT III) instantly identifies colorless diamonds and moissanites based on their thermal and electrical properties. In a new ergonomic design with a rubberized anti-slip grip, the unit can instantly distinguish natural colorless diamonds as small as 0.02ct and differentiate them from moissanites, cubic zirconia, and other diamond simulants, including colorless sapphire.
Another PRESIDIUM DIAMOND VERIFICATION INSTRUMENT® is the Synthetic Diamond Screener II (SDS II), which is used to distinguish Type IIa colorless diamonds from natural Type Ia colorless diamonds by measuring the stones' UV light transmittance. The unit gives clear and accurate results within two seconds and is suitable for both loose and mounted stones with an open-backed setting, as small as 0.02ct.
We recommend using the Presidium Multi Tester III first to determine if an unknown colorless stone is a diamond before testing it with the SDS II to check if it is a natural or Type IIa diamond (CVD/HPHT diamond). The SDS II has been ASSURE TESTED by an independent third party through ASSURE program and achieved 100% Laboratory-Grown Diamond Referral Rate.
The Presidium Electronic Gemstone Gauge (PEGG) is the industry’s first digital gemstone gauge, which is a complementary instrument to our range of diamond testers. It is a portable carat converter that can differentiate laboratory-grown Type IIa colorless diamonds from natural Type Ia colorless diamonds, with accurate results. Recognized globally as the most reliable digital gauge for measuring gemstone dimensions, the unit also comes with the Presidium Gemstone Weight Estimation Table for converting millimeters to carat weight in brilliant-cut diamonds.
Another complementary product to Presidium diamond testers is the new and improved Presidium Carat Scale – 100n (PCS-100n) measures gemstones up to 100.00 carats without the need to be calibrated each time the scale is shut off. The PCS-100n comes with a corresponding weight reference of 100.00ct/20g for calibration. This compact and portable scale can also be powered by a USB adaptor.