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