Gold coins are made mostly or entirely of gold. Gold has been for coins practically since the invention of coinage, originally because of gold's intrinsic value. In modern times, most gold coins are for collectors, or as bullion coins. Gold Bullion Coins whose nominal value is irrelevant and which serve primarily as a method of investing in gold. Gold has been as money for many reasons. It is fungible, meaning that it trades easily, with a low spread between the prices to buy and sell. Gold Coins are easily transportable, as it has a high value to weight ratio, compared to other commodities, such as silver. Gold can be into smaller units, without destroying its value; it melts into ingots, and re-coined. The density of gold is higher than most other metals, making it difficult to pass counterfeits. Gold is extremely un-reactive. The scarcity of gold stabilizes its value. Precious metals in bulk form are bullion, and trade on commodity markets. Bullion metals cast into ingots, or minted into coins. The defining attribute of bullion is that it is valued by its mass and purity rather than by a face value as money. While obsolete gold coins collected for their numismatic value, gold bullion coins today derive their value from the metal content and viewed by some investors as a "hedge" against inflation or a store of value. Many nations mint bullion coins. The European Commission publishes annually a list of gold coins, which are as investment gold coins in all EU Member States. The list has legal force and supplements the law. South Africa introduced the Krugerrand in 1967 to cater to this market; this was the reason for its convenient and memorable gold content — exactly one troy ounce. It was the first modern, low premium gold bullion coin. Bullion gold coins are also in fractions of an ounce – typically half ounce, quarter ounce, and one-tenth ounce. Bullion coins sometimes carry a face value as legal tender, the face value is on the coin, and in order to bestow legal tender status on a coin, which generally makes it easier to import or export across national borders, as well as subject to counterfeiting. However, their real value is as dictated by their troy weight, the current market price of the precious metal contained, and the prevailing premium that market wishes to pay for those particular bullion coins. The face value is always significantly less than the bullion value of the coin. Legal tender bullion coins are a separate entity to bullion gold. One enjoys legal tender status; the latter is merely a raw commodity. Coins are usually made of an alloy as other metals are into the coin to make it more durable. Fineness is the actual gold content in a coin or bar and expressed in grams or troy ounces. Karat weight is a unit of fineness for gold equal to 1/24 part of pure gold in an alloy. Pure gold is 1000 fine. Below is a karat weight to fineness conversion chart. There is a correlation between karats and fineness: 24 karats = 1000 fine, 23 karats = 958.3 fine, 22 karats = 916.6 fine, 21 karats = 875.0 fine, 20 karats = 833.3 fine, 18 karats = 750.0 fine, 16 karats = 666.7 fine, 14 karats = 583.3 fine, 10 karats = 416.6 fine.