Trying to Identify Hallmark on back of Old Indian Ring

I have an old Indian ring that has marks on the back. Looks like ‘I D’. I have no idea who this belongs to. I assume it is the maker. There are no other marks. Any idea on who the Hallmark represents? Appreciate any help. Thanks, Peggy

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This is a Navajo made piece, would guess in the 1980s. It is two letter stamps, so you think of a time when everyone was making this style because it was so popular, a hobby not a profession. Thanks for sharing.