The most economic investment in the bullion market is through Exchange-Traded Funds. These are traded at stock exchanges very similar to stocks. The annual expenses are low and are easily sold and bought from the stock market at an affordable stock commission. The producers of products buy bullion in bulk which is required in the manufacture of those specific products. These mainly include jewelry and electronics manufacturers. These customers contribute in the bullion market to get a steady and uninterrupted supply of gold necessary for their product's production. There are two types of customers in the bullion market. One is the investor and the other is the producer of goods who require precious metals for their production. Investors are those who buy precious metals as a hedge against inflation. They invest in bullion gold and when the moment is right, they sell it at a profit. Many factors are involved in this type of investment and it is not sure whether the investor will suffer a profit or loss. If the investor decides to take possession of the bullion, a heavy amount will have to be paid for its transportation and security. If the assistance of a firm for buying, selling and storing the bullion is sought, an annual fee for its storage and a buying and selling commission will have to be paid to them.  Gold bullion is traded through bullion markets or gold trading centers. The largest gold trading center is in London and is known as the "London Bullion Market". This market is a wholesale market which trades gold over-the-counter. Trading takes place amongst the members of the London Bullion Market Association (LBMA), under the supervision of the Bank of England. Other major centers for over-the-counter trading are New York, Tokyo and Zurich.  These centers are open 24 hours round the clock.  Gold bullion is the purest possible form of gold and traded in commodity markets. It may be in different forms like coins, ingots or bars. It may vary in size. Gold bullion is recognized by its purity and mass, not by its face value. The level of purity is not 100% but it must be above 99.5% pure. The purest form of bullion gold is the Canadian Gold Maple Leaf coin which is up to 99.999% pure.Gold Bullion Market