This free form cabochons is cut from koroit boulder opal from Australia.  It was hand cut in my cutting shop.  The polish is good the edges are cut for setting the stone in a bezel and the bottoms are flat.

FROM THE BOULDER FIELDS OF KOROIT

SIZE:(in millimeters) 40 x 22 x 3 MM THICK
WEIGHT(Carats): 36 
DOME: SLIGHTLY DOMED.
BOTTOM: FLAT.  
EDGE:  GOOD FOR BEZEL 
POLISH:  GOOD.