Quote Originally Posted by VeeDubb65 View Post
I think what you need to remember, is that we have degrees of precision here. ("significant figures" was the term we used in all of my physics/chem classes back in college)

We tend to think of 5/8 and 10/16 and 1710/2736 as all being the same measurement, but they're not. Even if the fractions reduce the same, using a larger denominator establishes a greater degree of precision in the measurement.

If something is sold as 5/8, that means that it is 5/8 when measured to the nearest 1/8. 1/8 is all the more precise the measurements are to begin with. If they were measuring to the nearest 1/16, then they would have been labeled that way.

Of course, glen's explanation is also dead-on, so that complicates matters even more. If you stick to measuring to the nearest 1/8, and a razor is just the tiniest bit closer to 6/8 than 5/8, the first time you hone it, it will drop down to just the tiniest bit closer to 5/8, so you could turn a 6/8 razor into a 5/8 razor by taking off 1/64. (in theory)
Think Europe - think METRIC!

John