Opal Historical SA Trade standards (1979)
This document has been extracted from the 1985 South Australian regulations. The original act was written in 1979. It could be said that the documentation was produced in order to clarify natural solid precious opals from both composite opals (doublets and triplets) and also provide a distinction between precious solid opal and precious Andamooka opal both as mined and as treated to look like black opal.
