Highly figurative 75.20ct Koroit boulder Opal

This exotic boulder opal is very well marbled with a swirling matrix that frames glittering pops of pure opal crystal. It has a glossy luster, and measures 38mm x 26mm x 8mm. This is an untreated boulder opal, it contains pure opal and matrix. This gem was sourced from the Koroit opal fields in the Paroo shire of southwest Australia.