Jewelers use Krohn Tivaclean. It is an electrocleaning concentrate for both metals and plastics.  Tivaclean is an orange powder that, when mixed with water, ( 8 oz. to the gallon ) changes to a fluorescent green to insure full rinsing.  Tivaclean also contains anti-foaming agents for low sudsing and a deodorant to suppress odor.

Tivaclean is also a great ultrasonic cleaner. Tivaclean can be used at room temperature, however, heating the solution to a temperature between 160° and 180°F enhances its performance.