Hi, it appears that Olivia took the jis tables from one of my pages... I can't give you a reference for the data to proove its accuracy, but I spent about a year with a kanji dictionary and yahoo.co.jp searching before I found a Japanese industrial abrasives manufacturer that had a detailed JIS chart showing both the old and new JIS down to this level of detail in a gif image that copied into text format:
http://members.cox.net/yuzuha/jisgrits.html
(I did not list the old JIS standards to that detail since the sedimentation tube method is obsolete but I did list a partial comparison of the old and new JIS on my Shapton grit page
http://members.cox.net/yuzuha/jisgrit1.html The yellow numbers on here are purely theoretical and I calculated them for comparing Shapton's grading system to other stones and micron graded powders etc. )
Alas, I can no longer point you to the original site where I found the JIS information because the PC I had all that on died several years ago.... I also no longer have the complete details of the old JIS standard (you can download the standards from the JIS organization in English or Japanese but they charge a considerable fee to do so).
One really interesting thing to note on the detailed table though is the maximum size. 8000 grit can have a few percent 6 micron particles, which can put some dandy scratches in mean 1.2 micron finish. Also the 3% tails are interesting... The 3% below .6 microns is not very important but again it allows 3% to be between 3.5 and 6 microns and still be listed as 8000 grit!
BTW, I discovered that some of you also hang out on knife forums but some of you may not.... you can still find some useful stuff in the useful links sub forum of the kitchen knife forum over there...
http://www.knifeforums.com/forums/showtopic.php?tid/759892/
http://www.knifeforums.com/forums/showtopic.php?tid/759541/
for example.
Lots of sources for stones anyway:) Might find some razor discussion in the "kitchen" and "keeping sharp" forums too.