Hi Cheryl, good looking piece.
Checked Barton Wright's "Hallmarks of the Southwest" for your mark.
No single G marks listed. Best possibility is Navajo artist Jerry Cowboy who did use a C mark.

Navajo silversmith Carl Begay used the C mark, but with a symbol (usually a sun).
Navajo silversmith Cecil Nez also used the C mark, but he specializes in nugget work.
Pat.
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