Clarity-Enhanced Glass Imitating Emerald
The Carlsbad lab received a transparent green octagonal step cut for identification. This stone visually resembled emerald due to its rich green color and large fractures. However, its single refractive index of 1.510 was not consistent with emerald’s double refractive index of 1.577 to 1.583.
Examination with a standard gemological microscope revealed no natural inclusions. Instead, it showed rounded gas bubbles in the body as well as flattened gas bubbles in surface-reaching fractures (figure 1). This stone has also been examined with FTIR and long-wave UV. When observed with long-wave UV, the fractures emitted a weak white fluorescence while the body of the stone showed a very weak blue fluorescence. The presence of these features was enough to conclude it had been clarity enhanced.
Additionally, rounded gas bubbles separate from fractures, an RI of 1.51, and the sample’s FTIR spectrum (figure 2) were consistent with manufactured glass.
These gemological properties and observations identified the material as clarity-enhanced manufactured glass. Due to emerald’s high value, it is common for imitations to show up in the market. Items such as this demonstrate the need to always be cautious when purchasing gemstones.
