GEM Electronic Diatest 2000 (c.1970s-1980s)

The Diatest 2000 is an early desktop gemological testing instrument manufactured by GEM Electronics in Taiwan during the late 1970s and 1980s. Housed in a durable dark clamshell casing, the device features a clean, minimalist faceplate equipped with "Power" and "Ready" indicator lights, a specialized testing tray to anchor loose gemstones, and a wired, copper-tipped thermal probe. The inner lid contains detailed operating and calibration instructions, making it a highly recognizable artifact from the early era of electronic gem testing.

The device relies exclusively on thermal conductivity technology to differentiate natural diamonds from simulants. Because natural diamonds possess an extraordinarily high rate of thermal conductivity—transferring heat much faster than almost any other material—the tester measures the speed at which heat is drawn away from the probe's tiny heated thermistor tip. When pressed against a genuine diamond, the rapid heat dissipation triggers the dedicated "DIAMOND" indicator light on the deck.

Despite its reliability against older simulants like glass and Cubic Zirconia, the Diatest 2000 ultimately faded out of industry use due to the introduction of synthetic Moissanite in the late 1990s. Because Moissanite mimics the thermal conductivity profile of a diamond, it caused false positives on purely thermal testers, forcing the gemological industry to pivot toward advanced dual-testers that combine both thermal and electrical conductivity. Additionally, the desktop format was quickly made obsolete by the miniaturization of technology, which introduced the ultra-portable, instant-read handheld "tester pens" used by modern jewelers today.