Which property do moissanite testers test to distinguish from diamonds?

• A. Thermal conductivity
• B. Refractive index
• C. Electrical conductivity
• D. Magnetic properties

Answer: (C)

Electrical behavior is what moissanite testers use to tell moissanite apart from diamonds. Diamond is an electrical insulator with very high resistivity, so it conducts almost no electricity under the tester’s test conditions. Moissanite, made of silicon carbide, is a semiconductor and will conduct a measurable amount of current when probed. By applying a small electrical signal and checking how much current flows, the tester can differentiate the two: little or no conduction points to diamond, while detectable conduction points to moissanite. Some testers also use thermal conductivity, but for distinguishing these two specifically, electrical conductivity is the key differentiator.