I'm at work, and bored, so I did some looking and here's what I found:
not sure if these are P grits or what, they are definitely not "mesh"
Grit Micron
100,000 (1/4 micron)
50,000 (1/2 micron)
14,000 micron)
8,000 micron)
3,000 (6 micron)
1,200 (15 micron)
600 (30 micron)
325 (45 micron)
220 (60 micron)
180 (80 micron)
100 (150 micron)
Apparently aluminum oxide is availible down to .05 micron (500000 grit)
A table I found:
A snippet of an article:
Getting information on particle size is very difficult. This is understandable as this is one of the differentiators between polish quality companies. One company sells three different green rouges. There may be different materials added to each or most likely there is a difference in the chrome oxide quality and quantity. A smaller micron size being one indicator of higher quality. This makes it tough on us purchasers since we don't have the information. I was able to get information from one company's web site on particle size
COMPOUND MICRON SIZE
Red Rouge 3.5 to 5
Cerium Oxide 3.5
Cerium-R Oxide 1.2
On a telephone conversation with Matchless Metal Company a large supplier of abrasive compounds, they indicated the their chrome oxide was less than 1 micron. This is unverified information.
that's about all I can find, pretty general stuff..