Blue Sapphire Reportedly from Badakhshan, Afghanistan
Recently, Habib Khan (Royal Gems Stone, Bangkok) donated a parcel of more than 40 rough sapphires to the GIA laboratory in Bangkok. Mr. Khan reported that they were mined from a new deposit in Badakhshan Province of northeastern Afghanistan. A few days later, Kamran Wahidy from the city of Fayzabad informed author VP of a new sapphire deposit near Khash in Badakhshan. This site produces material similar to the stones presented by Mr. Khan. Previous discoveries of corundum around Khash have been reported (Fall 2007 GNI, pp. 263−265; Winter 2010 GNI, pp. 319−320). The samples (see figure 1) were blue, purplish, or near-colorless. The rough sapphires ranged from 0.9 to 19.6 ct and were transparent to translucent. Standard gemological testing revealed an RI of 1.760−1.768 and an SG of 3.71−3.98. The wide range in SG can be explained by the large pieces of lighter matrix attached to some of the corundum samples. The stones displayed weak orange to inert fluorescence under long-wave UV and were inert under short-wave UV. All samples were originally covered with a thick, dark greenish black skin that was removed to reveal the blue sapphire inside. Most samples still had some of this skin attached. The skin contained dark green spinel, phlogopite, chlorite, feldspar, amphibole, and tourmaline, which were identified by Raman spectroscopy. Flat negative crystal fingerprints were commonly seen; some contained CO2 bubbles and diaspore fibers that became visible at 60× magnification. The samples displayed ladder- or dust-like inclusions similar to those seen in sapphires from Kashmir (figure 2; see H.A. Hänni, “A contribution to distinguishing characteristics of sapphire from Kashmir,” Journal of Gemmology, Vol. 22, No. 2, 1990, pp. 67−75).
Crystal inclusions were identified (using Raman spectroscopy and the RRUFF reference database) as apatite, amphibole, mica, diaspore, chlorite, tourmaline, feldspar, and spinel. We also observed unidentified clusters of tiny black crystals and crystals that might have been epidote or allanite. FTIR spectroscopy revealed the presence of boehmite, kaolinite, and a peak at 3161 cm−1. LA-ICP-MS showed an iron content between 154 and 402 ppma, while gallium ranged from 7 to 11 ppma. If confirmed, the discovery of a new blue sapphire deposit near Khash could be interesting for the gem trade in Afghanistan. However, this new material represents a true challenge for gemologists working on origin determination, as its inclusion scene is, in some aspects, very similar to those in sapphires from Kashmir.