You may clean those clear gems on your jewelry such as diamonds, natural crystals,emeralds, amethyst, rubies, sapphires and all precious stones etc. in an ultrasonic cleaner if you wish. However, if there is any other type of stone in the setting than you should NOT use the ultrasonic cleaner. You can also clean gems with a mild liquid detergent and a soft brush. Dry with a non abrasive lint free cloth.