Practical Acid Kit for Testing Silver, Platinum, and Gold – Touchstone Jewelry Testing Tool Set Features: This kit is designed to help verify the gold content in various items. Ideal for testing jewelry, coins, antique gold, silver, platinum, and other collectibles. Suitable for testing gold items believed to be 10K, 14K, 18K, 22K, or 24K, as well as silver and platinum. The acid solution changes color based on the metal's purity, providing a simple and effective test method. Easy to use and convenient for on-the-spot metal verification. Specifications: Material: High-purity graphite stone and acid testing solution Graphite Stone Size: Approx. 4.1 x 1.1 x 7.2 cm (1.61 x 0.43 x 2.83 in) Acid Testing Solution Bottle Size: Approx. 3 x 1.2 x 4.7 cm (1.18 x 0.47 x 1.85 in) Total Weight: 90g Type: Jewelry Testing Tool Package List: 1 x Graphite Stone 1 x Bottle of Acid Testing Solution (3ml) How to Use: To test a gold item, rub the item on the touchstone to leave a visible mark. Apply a drop of the acid solution onto the mark. If the mark remains unchanged, the item is likely genuine and matches the tested karat. If the mark dissolves or changes color, the item may be lower in purity or not genuine. Note: Always handle the acid solution with care. Use in a well-ventilated area and avoid contact with skin or eyes.