In a pinch and don’t have any oxidizing supplies on hand? Use an egg! Boil egg, peel, chop and insert in a closeable bag. Add your silver and leave until the silver darkens to your taste. The color will go through the typical tarnish stages starting with yellow but eventually turns dark gray or black. This usually takes just a few hours but can take up to a day. Remove jewelry, wash and dry. Rub quickly with a polishing cloth or very fine steel wool, if you would like to highlight some areas.