Many people associate gold bullion bars with the bulky brick-like forms we imagine must sit in places like Fort Knox, Swiss banks, and the cartoon vault of Scrooge McDuck. But today, even in this age of electronic-fund transfers and smartphone payments, slender gold bars of a more modest scale (some weighing as little as 1 gram) are actively traded, hoarded, and even collected. Some of the most popular types of gold bars are Credit Suisse and PAMP, both produced in Switzerland. Gold-clad "art" bars are also sought.
To ensure that the gold bars people buy and sell are of uniform quality and composition, the London Bullion Market Association periodically issues what it calls its Good Delivery Rules for both the gold and silver bars that it oversees. The last update to these rules was in June of 2011. Among other things, the rules specify that the bars must be wider on their top surface than at their base and it is recommended that the weight of a gold bar not be stamped into its top surface since they must be officially weighed again anyway (information like serial numbers and the year of a bar's manufacture, however, are encouraged). Finally, bars must contain between 350 and 430 fine troy ounces, with "fine" defined as 995.0 parts per thousand fine gold.
All this might sound like a lot of fuss for a metal whose value fluctuates wildly and is most commonly associated with fine jewelry, but gold is not called a precious metal for nothing. In fact, it's a highly finite resource, so much so that some believe all the world's gold, including that which has been mined for almost 6,000 years, could fit into a 67-by-67-foot cube weighing not much more than 150,000 tons. That's a lot of gold to concentrate into one place, but spread across the world among all the people who want to use it as a hedge against inflation, as a component in electronics, or even as gold leaf for art or an edible decoration on a slice of chocolate cake, it's not that much.