Info needed on '70's braclet marked "BM"

I have a 3 stone Turquoise bracelet, … purchased in 1977. No Sterling mark, … but do to the tarnishing, I suspect IS Sterling. It’s a 3 banded open bracelet with good stones, … but simply marked “BM”. No other stamping is present. Has a ‘rope’ design around each mounting. I’ll supply photos as soon as I’m able to do so. From the seller, … believe it may have been Navajo (piece from Arizona).

photo will help, thanks

Sorry the photos are so bad, … but with the camera I have … lucky to have these. The stamping upon the bands are simply " B M " as stamped (minus the quotation marks). Not sure of the origin of the stones, … but purchased from a seller from Arizona in 1977. Any info would be a great help. I’ll try to improve the photos with my son’s help.
Best and thanks for any information.

INFO ON 1970’s Navajo Bracelet Needed

I suspect this is either “Bisbee” or “Blue-gem”, but I can only go by what is on line for details. The stones have obviously been processed, as there are minute spots of white within the matrix. The large stone in the center of the band has the most detail and a bit of what I’m assuming to be a small bit of Cu matrix.

NEW PHOTOS SUPPLIED on this Navajo late 1970’s bracelet.

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