Hi, the AU-53 grade is not available in the database. A Microsoft Access table seems to have a limit of 255 fields and the value table is very close to that limit. So we are not able to offer every possible grade, remember we include FSB, DMPL, FH, etc..
you can type in AU-53 manually when you enter a coin as the condition. But a value table will not have a separate field for AU-53 like it does with AU-50 and AU-55 so you would need to enter the value yourself.