GTE 2''x2'' Jewelry Acid Test Stone ? Perfect for Silver, Gold, Platinum More EASY to use and ideal for determining the karat value and purity of silver jewelry, scrap, bars, coins, and much more! This 2''x2'' GTE Acid Jewelry Test Stone works seamlessly with acid solutions to accurately test the purity of your precious metals. Simply scratch the test stone with your jewelry, apply a drop of acid, and watch the results appear! (Note: Acid solutions are sold separately.) Our goal is to make testing your jewelry FUN, FAST, and EASY! This 2-Piece Kit Includes: GTE 2''x2'' Test Stone: Brand new in box with a rubber backing to ensure non-slip testing on any surface. Easy-to-read instruction booklet: Clear and concise, so you can get the most accurate results every time. A MUST-HAVE for anyone who invests in gold, silver, platinum, or other precious metals! For any questions, don?t hesitate to contact us. We look forward to serving you!