I would say to forget the old crucible, smash it up to retrieve your
platinum and get a Wesco melting dish, and blast the heck out of it
(don't forget to use blue glasses) to get great platinum use the
inside of the dish and make it dance with the torch flame let it do
the waltz inside, it must get as bright as the sun, then with long
tongs grab the whole melting dish when red hot and dunk it in cold
water and flip it and do the same then you will be OK. Don't mind the
steam it will go.
You will know your platinum is good if you see a galvanized
appearance on the top of the button after it has cooled. It even looks
like small earth quake cracks on the top sometimes that is OK.
P.F.F. Hinged Ring Shanks