I haven't had direct experience in mounting coins for exhibition since they
are not a significant part of our collections.  However, I do regularly
examine metals objects, including some fairly erroded archaeological coins.
We have almost universally found that the use of fiber optic lights to
provide raking light is an essential part of conservation
examination/documentation of multitudes of objects, including two-dimensional
art (paintings, paper, etc.)

I would suggest that you experiment with  fiber optic light sources to
provide raking light across the coins in your exhibit cases and this will
certainly make the coins visually "legible", even without magnification.

Dave

David Harvey
Conservator of Metals & Arms
Colonial Williamsburg Foundation
P.O. Box 1776
Williamsburg, VA  23187-1776  USA
voice:     804-220-7039
e-mail:  [log in to unmask]