When we mention the price of gold it is per Troy Ounce, this is a system of units of mass used for precious metals and gemstones. This is not the same as the Avoirdupois Ounce which is used for every day purpose in The USA and not quite so much in the UK. The Troy Ounce is about 10% heavier than the Avoirdupois Ounce (ratio 192/175). All knowledge helps you broaden your understanding of our subject of investing and saving in gold.