Use soft brushes for hard gems. A popular tool of choice is a soft-bristle toothbrush. The brush must be soft; otherwise, you might do more harm than good to your stone or setting. A hard-bristle brush might even damage the metal holding your gems and diamonds. Better not chance it. To clean your jewelry, get a warm bowl of water and scrub with a few drops of ordinary liquid dish detergent.
Try good old-fashioned baking soda. Baking soda has an amazing amount of cleaning uses, and can also get the grime off of your jewelry. Combine the baking soda with water to create a paste, then use a soft brush to gently scrub your gems and metals. Next, dry and polish the ring with a lint-free cloth and your jewelry will shine. (If your jewelry is very dirty, a stronger chemical solution will get your diamonds and gems sparkling better.)