1、This detecting stone is used to verify the gold content in items 2、Apply a drop acid test on detecting stone, real gold will stay on the detecting stone, fake one will be dissolved or oxidized to blue 3、This solution works for testing any gold which you believe to be 10K, 14K, 18K, 22-24K, silver, and platinum pure 4、Acid changes color based on purity. Very easy to use 5、Ideal for testing jewelry, coins, antique gold, silver, platinum collectibles Features: 1. This detecting stone is used to verify the gold content in items. 2. Apply a drop acid test on detecting stone, real gold will stay on the detecting stone, fake one will be dissolved or oxidized to blue. 3. This solution works for testing any gold which you believe to be 10K, 14K, 18K, 22-24K, silver, and platinum pure. 4. Acid changes color based on purity. Very easy to use. 5. Ideal for testing jewelry, coins, antique gold, silver, platinum collectibles. Specification: Condition: 100% Brand New Item Type: Detecting Stone Material: Stone Color: As Shown in the Picture Weight: Approx. 55-65g Optional Type: Common, Superior (Small)Size:Approx. 71 x 41 x 5mm/2.8 x 1.6 x 0.2in Package List: 1 * Detecting Stone (Acid Testing Water Not Included)