When it comes to gold, the media often talks about 'London Gold'. In short, it is 400 ounces of 99.5% pure gold bricks stored in the underground vaults of the City of London.

So London gold has at least three conditions.

1, It is stored in London. The same brick stored in Zurich becomes Zurich gold, stored in New York becomes New York gold, and the same brick in London is priced differently from anywhere else. Why? There are shipping costs. The most active spot gold on the international market is London gold.

2, The purity of gold is not less than 99.5%. The purity of gold on the Shanghai Gold Exchange is 99.99% and 99.95%, which is higher than the purity of London gold.

3, The weight is 400 ounces a piece. Only 400oz (12.5kg) gold bricks are good delivery bricks. 1kg gold bricks are not good delivery bricks.

See the photo below of London gold in the underground vaults of HSBC in London. As you can see, each wooden shelf holds 80 gold bricks of 12.5 kg each, i.e., one ton of gold on each shelf.

In addition to the three basic conditions mentioned above, there is a fourth element.

Each gold brick is stamped with a number and a processor's emblem. The word hallmark in English first meant this emblem on a gold brick. The number of each gold brick allows the brick to be registered in the name of the owner, which is called allocated. If you want to trade this kind of gold brick, you have to go to the basement and find the brick with that number for delivery, which is very inconvenient. Therefore, the majority of gold bricks traded on the market are unallocated bricks, which do not need to be numbered and can be delivered when the number of bricks is correct.