How to Gold Perform a Float Test Checking if a gold metal floats in water is sometimes also referred to as the density test. It is one of the ways of substantiating a gold piece. It could be jewellery, gold coin and bullions etc. To know the density of a gold piece, you first measure the mass and then the volume. The density is therefore known by dividing the mass by the volume. This division would provide the density of your gold piece accurately. By standard, 24 karat gold has a density of 19.3 grams, while 18 karat gold has a density of 15.6 grams, and 14 karats are 13.1 grams, all per cubic centimetre. So, for instance, this means that each atom of the 24 karat gold parts is heavy. So when you measure a 24k gold and get a result far from these, you can identify it is fake gold. When purchasing, the weight is also usually inscribed in a privy place. If the weight you measure is far from what is inscribed, you know what it is that you are purchasing or have purchased. With this, you already know if it is fake or real even before putting it into the actual water test.