The value of bullion is affected by three factors: metal, weight and purity. The metal the bullion consists of is obviously important in determining its overall value: gold is worth more than silver, while platinum is worth more than gold. The weight of bullion is usually measured in troy ounces, where one troy ounce is equal to approximately 31g. Purity also varies widely in bullion, though many countries release coins with 99.99% purity, which is as close as one can practically get to pure.

The average minting of a bullion coin is less than 10,000, one of the reasons they are so popular with collectors. Extremely limited presses are also relatively frequent, with countries sometimes releasing as few as 20 to 50 of a certain bullion coin. Silver coins, particularly, are popular with collectors; because of the relatively low worth of their metal, they are cheaper in general. For this reason, silver bullion coins, more than gold or platinum, are often valued substantially above the market value of silver.

At this point, most major countries offer at least one type of bullion coin. Usually these coins will have one main symbol they use each year, though some nations choose to keep the same theme but alter the image yearly.