Features: Special designed to verify the gold content in items.Acid changes color based on purity. Very easy to use.Ideal for testing jewelry, coins, antique gold, silver, collectibles, and more. Apply a drop acid test on touchstone, real gold will stay on the touchstone, fake one will be dissolved or oxidized to blue.Works for testing any gold which you believe to be 10K, 14K, 18K, 22-24K, silver, and pure.Specifications: Condition: 100% Brand NewOptional Type: Common, Superior (Small)Size: Superior (Small): Length: Approx. 6cm / 2.4in, Width: Approx. 3.4cm / 1.3in Common: Length: Approx. 4.5cm / 1.8in, Width: Approx. 3.9cm / 1.5inPackage List: 1 x Touchstone (Acid Testing Water Not Included).Note:Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.