Silver test solution sells for about $5 a bottle on eBay. I've used it to deblob gold dollars several times. Sometimes it works, if the blob is silver solder. It hasn't affected the underlying gold coin.
"Two minutes ago I would have sold my chances for a tired dime." Fred Astaire
Silver test solution would work if it is silver solder, if it is gold solder I would not expect it to work. For gold solder you would use gold test solution but but the gold test solution will also attack the surface of the coin. But if the karet of the solder is lower than that of the coin it will attack the solder faster. If the solder is a significantly lower Karet you might be able to dilute the solution some so that it doesn't attack the coin but that would probably a little hit and miss.