Toothpaste is good but the best cleaner is baking soda. Make a paste of baking soda and water and use with a cloth to polish. If there are crevices that are hard to reach leave the paste on for a half hour then clean with tooth brush. Tarnish on silver is oxidation that is neuturalized by baking soda. If the tarnish is real deep in designs put in a pan with a sheet of aluminum foil in botton. Simmer in a baking soda solution for around a half hour. Make sure silver item is completely covered in solution. Stones will not be harmed unless they are plastic.