Practical Acid Kit Silver Platinum Gold Test Stone Jewelry Tool Set Features: This kit is used to verify the gold content of items. Ideal for testing jewelry, coins, antique gold, silver, platinum collectibles and more. This solution works to test any gold that you think is 10K, 14K, 18K, 22-24K, silver and platinum pure. The acid changes color depending on the purity. Very easy to use. Specification: Material: High Purity Graphite Stone & Acid Test Water Graphite Stone Size: Approx. 4.1 * 1.1 * 7.2 cm / 1.61 * 0.43 * 2.83 inch Acid Test Water Size: Approx. 3 * 1.2 * 4.7 cm / 1.18 * 0.47 * 1.85 inchTotal weight: 90gType: Jewelry Tools & EquipmentPackage List:1 * Graphite Stone3ml * Acid Test WaterNote:How to use:If you want to test whether your gold ring is real or not, you just need to rub black stone and leave a small sample on the stoneApply a drop of this solution to a small sample of the item to be tested on the test stone.Then the real gold will remain on the test stone, fake gold will dissolve or oxidize to blueIf the sample disappears, the item is below the carat of the solution.