Precious metal "precious" metal can also be determined by high demand or market value. Precious metals in bulk form are known as bullion and are traded on commodity markets. Bullion metals may be 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. The level of purity varies from issue to issue. "Three nines" (99.9%) purity is common. The purest mass-produced bullion coins are in the Canadian Gold Maple Leaf series, which go up to 99.999% purity. A 100% pure bullion is
Commodity price index the index. The first such index was the CRB ("Commodity Research Bureau") Index, which began in 1958. Due to its construction it was not useful as an investment index. The first practically investable commodity futures index was the Goldman Sachs Commodity Index, created in 1991 and known as the "GSCI". The next was the Dow Jones AIG Commodity Index. It differed from the GSCI primarily in the weights allocated to each commodity. The DJ AIG had mechanisms to periodically limit the weight of any one commodity and to remove commodities whose weights became too small. After AIG's financial problems in