Two Synthetic Diamonds Identified in a Parcel of 7,000 Melee-size Yellow-Brown Diamonds

摘要

In late 2013, the Laboratoire Francais de Gemmologie analysed a parcel of 7,000 melee-size (1 to 2.5 mm in diameter) yellow-brown diamonds. They were presented as natural 'cognac' diamonds, and reportedly had already been screened for synthetics. The first step in our examination was to observe all the diamonds in long- and shortwave UV radiation (see Figure 15). Two of them emitted an intense green luminescence to short-wave UV, but remained inert to long-wave UV radiation (e.g. the gem at J18 in Figure 15). Such behaviour may be indicative of high-pressure, high-temperature (HPHT)-grown synthetic diamond (see, e.g., Shigley et al., 1986).