Pyrope-Almandine Garnet in Sapphire Host
In gemology, garnet occurs in a wide variety of colors, including red, orange, yellow, and green. Garnet is also found as inclusions in diamond, quartz, topaz, aquamarine, and zircon (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 1, ABC Edition, Zurich, 1986, pp. 158–160).
GIA’s Bangkok laboratory recently received a 3.97 ct transparent greenish blue sapphire for a colored stone identification report. Standard gemological testing and advanced analysis revealed properties consistent with natural sapphire. Interestingly, microscopic examination with a combination of darkfield and oblique fiber-optic illumination revealed a well-formed brownish orange crystal cluster with reflective needles (see above). The crystal was singly refractive, and Raman spectrometry matched it with pyrope-almandine garnet. Sapphires with garnet inclusions are rarely seen in laboratory examination, although they are occasionally found in samples from Tanzania and the state of Montana (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 3, Opinio Publishers, Basel, Switzerland, 2008, pp. 228–242).
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