Koroit boulder opals are unlike any other. The color is often inter dispersed as glittery flashes and veins. This is in contrast to the seams more common of Opalton. Some, like this one, are even double sided with color!
Photos give a very poor representation of this material. Watch the YouTube video linked below for a better idea of what this gorgeous piece has to offer.
It measures 25 x 18 x 4 mm and weighs 3.01 grams.
https://youtu.be/H086fPTYZ2g