Coins are usually collected just as a hobby. But you can actually buy these things called gold bullion coins, which retain a value equal to their weight in gold, literally! Gold bullion coins are usually available in a variety of sizes, usually 1 troy ounce or less. There are so many world gold bullion coins released by various countries.

The South African Krugerrand was first issued in 1967. The Krugerrand is available in one, half, quarter, and tenth troy ounces. It has a fineness of 22 carats, meaning it is 91.67% pure gold. Over 46 million ounces of the South African Krugerrand have been sold through 2008. It was first minted to assist in marketing South African gold.

The American Gold Eagle was first issued in 1986. This coin is also available in the same sizes that the Krugerrand is in. It's also 22 carats. A single troy ounce Gold Eagle coin has a face value of $50, but the gold in the coin is worth over 18 times that amount.

The Mexican Gold Libertad was released in 1982. It's available in the 4 sizes mentioned above, as well as an extra twentieth troy ounce size. The interesting thing about the Libertad is that it's not just 22 carats. It's actually 24 carats, meaning that the coin is 99.9% pure gold. The Libertad is also available in silver, where sizes go up to a whole kilogram.

The Canadian Gold Maple Leaf is Canada's official gold bullion coin. Like the Libertad, it is released in five different sizes. The Royal Canadian Mint set new standard for gold purity with the Maple Leaf, as it released a special version coin in 2007 that was 99.999% pure gold, nearly no base metals. The same mint also produced a massive 100 kilogram gold bullion coin. Needless to say, only five were produced. The Maple Leaf's gold comes direct from Canada's mines.

The Austrian Philharmonic is released in five sizes, all with 24 carats. The largest size is the 1000 troy ounce coin, which equates to around 69 pounds. It has a face value of 100,000 euros, and 15 coins were minted in 2004.

As you can clearly see, the minting of gold bullion coins doesn't stop at the larger countries. It's a global thing, because these coins actually help an economy (see Krugerrand). Many of these coins, although they have a face value, end up being worth around $1000 no problem, but you have to take size into account. A 1/20th troy ounce coin will probably be worth 20 times less than a one troy ounce coin. Nevertheless, watch the price charts of gold and you're going to see a similar trend in almost every single one of the world gold bullion coins.