Age Determination of Zircon Inclusion in Kashmir Sapphire with U-Pb Dating

Zircon inclusions in two selected Kashmir sapphire reference samples and one faceted gemstone were studied by HR SIMS and LA-ICP-MS for U-Pb age determination. The two independent analytical methods result in the same conclusion that the zircons have crystallization ages of 26-25 Ma. The provided result is a good reference for U-Pb age of Kashmir sapphire that can be used for origin determination in gemmological laboratories with LA-ICP-MS routine method. Additionally,cathodoluminescence imaging showed that the zircon inclusions in Kashmir sapphires have regular oscillatory zoning. High U concentrations of up to 20 000 ppm have been detected in the zircon inclusions.