Seiko accuracy standard gradings

1960

1961

1966

1968

1969

1970

1968:

4A 3A 2A=L4A A=L3A B=L2A C=LA D=LB LC E LD F=LE LF G

Source: https://www.tapatalk.com/groups/seikoholicssupportforum/seiko-accuracy-standards-mechanical-t51.html?sid=646be44a8dfcafe8c29c2c4299ec45b5