Help with Belt Buckle

Hello all,
I would appreciate any information on the pictured belt buckle. I acquired it a couple of years ago while in Arizona from a Navajo family. It measures 3 1/2 x 2 1/2, my scale reads 2oz or 60 grams on the gram scale. It has a D for a hallmark. I believe the inlay is turquoise and coral? I have no idea of its value, history, artist etc… Prior owner stated it was owned by a grandmother. That’s all I know about it. Internet searches have not been productive. Any help would be greatly appreciated. It appears unused and hesitant to even wear it not knowing more about it. Thanks

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