SS Grading System
 

My kids got me for 18/10 ss pots Christmas one year so I didn't have a
choice in design or quality and was shocked when I found out how much
they were especially since there are only 5 pots with lids! I never
knew what the 18/10 referred to. I asked on the teflon thread then
since I had extra time did a little research. Here's what I found. The
numbers refer to the percentage of chromium to nickle in the ss alloy so
18/10 means 18% chromium to 10% nickle.
source - http://www.kitchenfantasy.com/shoppi.../stainless.htm