Rings live the hardest life of any jewelry, so it helps to know your stone. Spinel, at 8 on the Mohs hardness scale, handles daily wear easily. The garnets, tsavorite, tourmaline, rubellite, amethyst, and quartz run 6.5 to 7.5 and do well with ordinary caution. Fire opal, labradorite, and the opals sit at 5.5 to 6.5, occasion stones, best removed for anything rough. Every one of them cleans with warm water, mild soap, and a soft cloth, and none belongs in an ultrasonic cleaner.