Vintage Victorian 14k Solid Gold Australian Black Opal Ring

The setting is true antique, but the opal was added on afterwards, it’s a black opal sugar treated 3.06 grams Ring size 4.75 Sugar and acid treatment is one of the most commonly used methods to enhance opal. In the trade, this treatment is usually applied to matrix opal from Andamooka, Australia, a particularly porous material. The finished product is often referred to as “Andamooka matrix opal” or “Andamooka rainbow matrix opal” by the trade. This treatment was presented as a hot sugar bath followed by a hot acid bath (G. Brown, “Treated Andamooka matrix opal,” Summer 1991 G&G, pp. 100–106). The chemical reaction between sugar and acid then deposits carbon to the porous structure of the opal as black dots. The treatment darkens the background color of the opal and therefore makes the play-of-color stand out more.