Platinum Cerium is the ultimate grade of Cerium, it is for experienced users that wish to achieve a mirror polish on stones or glass. Often called French Cerium, it is 100% pure Cerium. One of the best all purpose polishes, cerium will polish quartz, agate, opal, obsidian, etc. Cerium is the perfect starter polish and will not break the bank. All Cerium grades work best with leather for stones, and felt for glass. Simply mix the polish with a little water to create a thin paste and apply generously to polishing surface. Use minimal water to keep the piece cool, and prevent washing away of good Cerium during polishing.