Recently, the author examined a 6.85 ct black opal cabochon, likely from Ethiopia due to the digit pattern of its play-of-color (B. Rondeau et al., “Play-of-color opal from Wegel Tena, Wollo Province, Ethiopia,” Summer 2010 G&G, pp. 90–105; B. Rondeau et al., “On the origin of digit patterns in gem opal,” Fall 2013 G&G, pp. 138–146). This opal contained several inclusions, such as black spots concentrated along pits and scratches, indicating that it was treated to produce a darker color and enhance the play-of-color phenomenon. Additionally, metallic octahedral crystals were identified as pyrite by Raman analysis. Interestingly, fiber-optic illumination revealed whitish snowflake inclusions (see above), which were identified as aragonite through Raman analysis. To the author’s knowledge, these are the first documented aragonite snowflake inclusions in opal.
Recently, the author examined a 6.85 ct black opal cabochon, likely from Ethiopia due to the digit pattern of its play-of-color (B. Rondeau et al., “Play-of-color opal from Wegel Tena, Wollo Province, Ethiopia,” Summer 2010 G&G, pp. 90–105; B. Rondeau et al., “On the origin of digit patterns in gem opal,” Fall 2013 G&G, pp. 138–146). This opal contained several inclusions, such as black spots concentrated along pits and scratches, indicating that it was treated to produce a darker color and enhance the play-of-color phenomenon. Additionally, metallic octahedral crystals were identified as pyrite by Raman analysis. Interestingly, fiber-optic illumination revealed whitish snowflake inclusions (see above), which were identified as aragonite through Raman analysis. To the author’s knowledge, these are the first documented aragonite snowflake inclusions in opal.
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