Belemnite, opalized fossil pipe squid, from Coober Pedy (South Australia). Pinfire green, orange red and a little blue colours. The sandstone inclusions show the natural stone. Drilled and ready to be worn on a leather cord or choker. Could also be set into a pendant. As can be seen from the photos it could be worn both ways!
Opal weight is 12.95 ct and size is 9.4 x 27.3 mm.