An electrical conductivity tester checks whether a stone conducts electricity. Many moissanites conduct, and most near-colorless diamonds do not.
In more detail
In GIA's 1997 study, 13 of 23 moissanites conducted. Some gray and blue diamonds conduct too: type IIb diamonds, colored by boron. So a “moissanite” reading on a blue or gray stone needs a laboratory. Combined testers pair a thermal reading with a second test.
Related terms
- Thermal diamond tester: A thermal diamond tester measures how fast a stone draws heat from a hot tip. Diamond conducts heat very well, so it reads “diamond”.
- Screening device: A screening device separates natural diamonds from laboratory-grown diamonds and simulants. Most answer Pass (natural) or Refer (send to a laboratory).