When you are buying gold coins these are the things to look for: Type of coin - Eagle, Sovereign etc. Size of coin - These can vary also. Sometimes measured in value and sometimes in weight. Face Value - 1 dollar or five dollar or even 10 dollar (for US or Canadian coins) for example. Weight - Usually measured in troy ounces or part of an oz but grams have also become a popular weight measurement recently. Fineness - (999% fine) Amount of gold compared to other metals such as silver.