I also believe a binocular microscope is a must for the really nitpicky cleaning of coins. You really dont need much more than 10x because you can see everything you need to at this magnification. The finest needle you can find (embroidery needle) looks like a club. You can always buy higher power eye pieces if you think you need them. These are not too very expensive on
Ebay. Just remember, many coins are cleaned using
cheap monocular loupes also. I personally like a binocular
type headpiece at 7.5x called an "optivisor" for most of my
work, as it keeps both
hands free. If you really need to get up close and personal, you won't go wrong with either of these. It is more a question of what you can afford, a Yugo, a Chevy, or a Lexus.
Regards
Chuck T