Density is a physical property that is determined by dividing the mass of a given amount of a substance by its volume. It is often reported in units of g/mL, which means 'grams per milliliter'. Density is an intensive property because the density of a pure substance will be the same no matter how much of it you have. For example, the density of pure gold is g/mL. This means that whether you have .5 grams or grams of pure gold, the density will always be g/mL when tested. Knowing this standard value enables jewelers to determine whether or not an item is pure gold.