Which variety of grit should be used to sharpen a dental instrument to be used for tooth preparation?
Stationary oilstones are available in coarse, medium or ﬁne grit. 
Only a ﬁne grit stone is suitable for the ﬁnal sharpening of dental instruments to be used for tooth preparation. 
Coarse and medium grits may be used for initial reshaping of a badly damaged instrument or for sharpening other dental equipment such as bench knives. 
Coarser stones cut more rapidly, but produce a rougher surface. 
If the use of two or more grits is required, the coarser is used as little as needed for reshaping and then the ﬁnal sharpening is done with a ﬁne stone.

Ref: Sturdevant's art and science of operative dentistry. 4th edition page 317
Very coarse
Coarse
Medium
Fine