The weights and purity displayed on coins and bars refers to the pure metal content. The overall weight of the coin/bar will be greater depending on how many other metals are alloyed with gold. The weight of a coin usually is measured in troy ounces.
Troy ounces weigh slightly more than regular ounces, with 31.1 and 28.3 grams in each respective measurement. Most coins come in 1/10, ¼, ½ and 1 troy ounce increments. Many coins come in different amounts, however, so always pay attention to the weight and purity. This is important to know so that you can compare the price of a coin to the spot price of gold.
But I’m getting ahead of myself; I haven’t explained the spot price yet! Click here for Spot Price Explained.