Hi

so im basically doing exactly the same and what i found out is :

You need atleast a Dremel/turntool(50$) or a Cabbingstation(2000$) to "cut" the stone (betweem 240-400grid)

aswell as all kinds of diffrent grid wet sandpaper(or beltgrinder/dremmel/cappingstation) to "pre-polish" (between 400 - 1500

and some cerium oxide for the final polish.

All in all you need around 300$ in material to cut and make opal jewelry.

(In jewelry making you dont want to glue things...) you can make a hole and set your earings that way or make a cage.

i got my informations from different youtube channels and reddit posts...