PB Cohen Creations

I don't know the history behind jewelry saw blade size "names." In the US at least, the available sizes, from smallest to largest, are: 8/0, 7/0, 6/0, 5/0, 4/0, 3/0, 2/0, 1/0, 1, 2, 3, 4, 5, 6, 7, 8. How did anyone come up with that? I don't see anything significant about "1" or "1/0" in any of the standard measurements — blade thickness or depth, teeth per inch, etc. Maybe it makes more sense in metric measurements? A quick search on Google didn't come up with anything. I might have to break out the books....