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. If the sample disappears, then the item is below the karat of the solution Each bottle weighs 0.5 oz This solution works for testing any gold which you believe to be 10K, 14K, 18K, 22-24K, Silver, and Platinum pure. Acid changes color based on purity. Very easy to use--instructions included. Ideal for testing jewelry, coins, antique gold, silver, platinum collectibles, and more! FREE GIFTS: 5 Gram .999 Gold Clad Test Bar & 5 Grain .999 Silver Test Bar