According to the inquiry of CRD Clayday Jewelry official website, the minimum amount of gold bars purchased by banks is 10g. Gold bars are large and small, and the small ones are 10g, 20g, 50g, 100g, etc. The big ones are standard gold bars circulating in domestic gold exchanges or markets, and their standard weight specifications are 10g, 30g, 50g, 100g, 300g and 500g respectively.