When I used to do this with scrap silver, before the bottom fell out of the silver market due to digital photography, there was very little "waste" less than 1 percent gross per troy ounce, clean the material first to get rid of any surface material that shouldn’t be there, that cuts the "slag" waste produced to less than 1pct, dead skin, hair, glue or paste will all cost you money if it is still on the product when you melt it down

I always did it myself with a crucible and a gas ring off the cooker so don’t know the cost if you wanted to have it assayed (melted and stamped by a jeweller has proof of what it is) if you use a crucible and do it yourself over the cooker make sure the room is well ventilated, it smells for days

One thing I did learn was to have documented proof of the gold or silver you were melting down yourself with accurate weights, photos and descriptions of any assay markings on the jewellery to prove that it was indeed the grade of silver or gold you purport it to be when it comes time to resell it.