This matched pair is cut from tiffany stone, which is an opal beryllium Flourite also know as Bertrandite from Utah  in the U.S.A.  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.

SIZE:(in millimeters) 19 x 13 x 3 MM THICK EACH STONE.
WEIGHT(Carats): 20.5 TOTAL WEIGHT OF BOTH STONES.
DOME: SLIGHTLY DOMED.
BOTTOM: FLAT.  
EDGE:  GOOD FOR BEZEL 
POLISH:  GOOD.