gems, opal, Iran, blue opal

Gem-grade blue-green opal, traditionally sourced from Peru, has recently been discovered in Iran, approximately 110 km northwest of Shahr-e Babak in Kerman Province. According to Makhmout Douman (Arzawa Mineralogical Inc., New York), mining at this new locality had nearly ceased by October 2007 due to groundwater intrusion, and few polished stones have been produced because of the fractured and thin nature of the rough. Mr. Douman loaned GIA two cabochons (2.40 and 2.59 ct) and one rough piece for analysis. The cabochons showed bluish green and green-blue color, were translucent, and had refractive indices of 1.45 and 1.47, respectively, with specific gravities of 2.06 and 2.00. No reaction was observed under a Chelsea filter or UV light, and a 600 nm cutoff was seen in the spectroscope. Microscopic examination revealed milky white clouds and, in one sample, a moss-like inclusion. Although the 1.47 RI is slightly above the typical opal range (1.44–1.46), Raman spectra matched those of standard opal. Near-IR spectroscopy confirmed hydroxyl-related features characteristic of opal, while EDXRF analysis detected major Si, minor Cu, and trace Fe. UV-Vis-NIR spectroscopy indicated Cu²⁺ absorptions between 527–1176 nm, confirming copper as the chromophore responsible for the opal’s blue-green coloration.