Ron Guth:
The following diagnostics have been seen on a counterfeit 1912 Indian Head Eagle: 1) shallow depression in the field to the left of Liberty's brow; 2) oblong depression on jawline; 3) another shallow depression in the field above the eagle's tail at the lower point of an imaginary triangle created by the depression, the M of UNUM, and the final A of AMERICA; and 4) tiny depression below and left of center of the O of OF.
"1912 Indian head $10 Gold" by Brian Sillima, NUMISMATIST, May 2007, page 117