Coming from the land of opals I have encountered the problem
hundreds of times. I also have customers come in with opal they
have found in the tailings of the mines. The cutters at Lightening
Ridge and the other Opal towns give them a quick polish for a few
bucks. They never give you a setting edge so I cut it myself and
do not use any complex tools. You can file opal or use a small
rotary disk to cut it.THE SECRET IS DON’T HEAT IT. Keep it cool do
it slowly. After cutting emery the surface it is easy and use many
grades to the finest you can get. Then with a felt rotary buff
about 2cm in diameter or 3/4 of an inch and about 3/10ths of an
inch wide. You can get them from Rio Grande I just can’t find the
cat for the number but I use their one.20 Then get some TIN OXIDE
it is perfect I use nothing else. Mix the powder with water and
dip the spinning disc in it and slowly polish the opal. BUT DO NOT
LET IT GET DRY OR DISASTER. It will craze and you have to emery it
down again. I drip extra water on it all the time. When the polish
is high I do use a drier paste but only a second at a time and let
the surface cool and wash in water the a little more. You can get
a perfect job.20 Sounds hard but it takes no time when you are use
to it but KEEP IT COOL. I do recomend Tin Oxide I have seen others
used but it works the best with small tools. Hope this helps Phil