Recent developments in gem testing

Abstract

Thermal conductivity is a test used mainly for diamond and its simulants. At room temperature the thermal conductivity of a single crystal diamond varies from 1000 W m⁻¹°C⁻¹ for Type I stones to 2600 W m⁻¹°C⁻¹ for Type IIa stones. For comparison with simulants of diamond, cubic zirconia has the value 10 W m⁻¹°C⁻¹; corundum has 40 W m⁻¹°C⁻¹ (the highest value shown by any of the diamond simulants).