hi;

I have few older US stamps (mostly used) (pre 1900), and I find it
hard to check which color some of these are. I was wondering if there
is some kind of machine which will make this task easier.

Using the color gauge such as this one

http://www.subwaystamp.com/prodinfo....mber=ZGKCOLTCG

helps a little, but some of the stamps I have are used and hard to be
sure which color it is in terms of if it is deep or light shade of the
color.

thanks,
Nasser