Feature: This kit is used to verify the gold content in items. Apply a drop of this solution to a small sample of the item to be tested onto the test stone. Real gold will remain on the touchstone, while counterfeit metal will dissolve or oxidize to blue. If the sample disappears, the item is below the karat rating of the solution. This solution works for testing gold items suspected to be 10K, 14K, 18K, 22K, or 24K, as well as silver and platinum. The acid changes color based on purity. Very easy to use, ideal for testing jewelry, coins, antique gold, silver, platinum collectibles, and more. Warm Tips: To test if a gold ring is real, simply rub it on the black stone to leave a small mark, then apply a drop of testing acid to the streak. Real gold will remain on the touchstone, while fake metal will dissolve. Specifications: Type: A/B/C (Optional) Material: High purity graphite stone and acid testing liquid Size: Acid testing liquid: 4.5 x 3 cm / 1.8 x 1.2 in (3 mL) Graphite stone: 8 x 5.5 cm / 3 x 2 in Quantity: 1 set / 1 piece Note: Size measurements are manually taken and may have a 0–2 cm variation, which is considered normal. Due to differences in monitor displays, the image may not reflect the actual color of the item. Thank you. Package Includes: 1 pc acid testing liquid (3 mL), or 1 pc graphite stone, or 1 set acid testing liquid and graphite stone.