Hi Guys,
so last weekend i was digging through an old shed at my house and came across an item i never noticed before. It appears to be an oil stone but is a very fine grit, it has a depression in the centre from being used to sharpen blades.

i know the guides on here say to use 400grit sandpaper, is there any harm in starting lower i only managed to find 180 grit wet and dry paper tonite and was going to have ago lapping it but figured i would ask first.


Also if i post some pics of it is there a chance someone might know what it is? i sense it being nothing more than a man made oil stone but im living in hope i found a gem


Kris