Presidium DiamondMate
Presidium DiamondMate
The Singapore-built thermal-conductivity tester for rapid diamond-versus-simulant screening
The Presidium DiamondMate is a compact, battery-operated thermal-conductivity tester manufactured by Presidium Instruments of Singapore, designed to distinguish diamond from common simulants such as cubic zirconia, glass, and synthetic spinel by measuring the rate at which heat dissipates through the test stone. Diamond's exceptionally high thermal conductivity — among the highest of any material at room temperature — produces a characteristic response on the instrument's scale that separates it from simulants whose thermal behaviour is markedly different. The DiamondMate is widely used in retail, wholesale, and pawn-trade settings as a first-pass screening tool.
Operating principle
The tester applies a heated probe tip to the table of the stone and measures the temperature differential between the probe and the stone over a short interval. A material with high thermal conductivity draws heat away from the probe quickly, producing a small differential and a corresponding indication on the instrument's display. A material with low conductivity retains heat at the probe, producing a larger differential and a different indication. Diamond's thermal conductivity, at approximately 2,000 W/m·K, is far higher than that of cubic zirconia (around 2 W/m·K), glass (around 1 W/m·K), or the other common simulants, and the test reliably separates diamond from these materials.
The instrument indicates results through an LED bar graph, an audible tone, or both, depending on the model. The DiamondMate II and DiamondMate Pro variants offer different sensitivity profiles and different user-interface refinements, but the underlying test physics is consistent across the line.
The moissanite limitation
The principal limitation of any thermal-conductivity tester is moissanite. Moissanite — synthetic silicon carbide — has thermal conductivity in the same range as diamond, and a thermal-only instrument cannot reliably distinguish moissanite from diamond. A stone that tests positive on a DiamondMate may be diamond or moissanite; further testing is required to separate the two.
Presidium addresses this limitation through dual-mode instruments — the Presidium Multi Tester (PMT) and Gem Tester (PGT) — that combine thermal conductivity with electrical conductivity testing. Diamond is electrically non-conductive (with the exception of rare Type IIb material); moissanite is electrically conductive. The combination of high thermal and high electrical conductivity is moissanite; the combination of high thermal and low electrical conductivity is diamond. The DiamondMate alone does not provide this discrimination and should be used with awareness of the limitation.
Use in the trade
The DiamondMate is most useful as a fast first-pass screening tool: a stone that fails the test is unambiguously not diamond and not moissanite, and the gem can be excluded from the diamond inventory without further work. A stone that passes the test is either diamond or moissanite and requires confirmation through electrical-conductivity testing or full gemmological examination.
For retail counter use, the DiamondMate is well-matched to the workflow: handle in seconds, no calibration required for routine use, and a clear pass-fail indication that does not require interpretive skill. For wholesale, lab, or fine-trade work, the dual-mode instruments or a refractometer-and-spectroscope examination are more appropriate, as the moissanite ambiguity is a real risk in the modern gem trade and a single-mode thermal tester does not address it.
Calibration and care
The DiamondMate's probe tip is the wear point. Routine cleaning with the supplied cleaning brush keeps the probe contact surface free of residues; replacement probes are available from Presidium and should be installed when the existing probe shows visible wear or no longer produces consistent readings. Battery life is the principal operating constraint; routine power-down between uses is the standard practice.