try calibrating your scale.
a clad half is 11.34 , a 40% is 11.5 , a 90% is 12.5, either that or its dunked in chrome. are you sure you know the ring test?
There are 40%'s post 1970 on planchetts that got through the QC but if you are over 11.5 you got a fake or you're in un-chartered territory.