Q-Tips and acetone as a solvent. Work slowly and carefully. Don't get acetone on the base material of the chip or it will smear over the inlay. Use several Q-Tips on each chip. Be prepared to destroy several chips till you get the hang of it. If the operator put lots of pressure on the cancel stamp, you may not be able to remove all the gold. You can get acetone at a paint store or auto supply house.

Takes me maybe 5 minutes per chip.