Gold, liquefied at a temperature of over 2,000 degrees Fahrenheit, is poured into a heated cast iron mold positioned on a balance to precisely measure it to desired weight. Seconds later, the newly-formed gold brick is quenched and cooled in a tank of water. It is then rubbed with a soft cloth and weighed before being marked by press or hammer with the refiner’s seal, a unique serial number, and its purity and weight. A gold bar has been made for investment.
The process described above is that which is used to manufacture the standard investment gold bar for trading on the major international markets, and is also held in reserve by the world’s central banks. It weighs 400 troy ounces (438.9 oz or 12.4 kg) and is known as a Good Delivery Bar. The London Bullion Market Association sets its requirements including a minimum fineness of 995 parts per thousand of gold and the various procedural requirements covering weighing, packing and delivery.