How should I proceed?

my grandmother gave me a ring she found randomly she doesn’t know who it belongs too but it is a united states marine corps ring and it has initials and a date in the back i like it and it was meant to be a gift cause i am enlisting myself soon but i would like to return it to the owner how should i proceed it ain't worth anything cause it is stainless steel and the ruby is fake but it probably has sentimental value my grandmother wanted to pawn it but when it wasn’t worth anything she gave it to me what way could i find the owner

How should I proceed?
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