For as much information as this cuff gives me, I cannot figure anything out. Any help would be appreciated! 
signed Lincoln, T.L. Hallmark, and BGM hallmark
Hey Linds,
You probably already did this, but in case you didn’t, scroll to the bottom of the 'B’s… #24 unidentified mark BGN… It looks A LOT like your BGM mark.
Beautiful piece, btw!
BGM is for B.G. Mudd, he is a manufacturer here in Gallup. The silver is casted and a Navajo artist will do the inlay work. You can find B.G. Mudd pieces in lots of places, airports, Grand Canyon gift shop. I don’t know if Lincoln is an artist last name that had something to do with making the piece, I assume he/she did and marked the piece. Thanks for sharing.
I also have a BG Mudd bracelet that is about 18 years old. Well loved and worn often! I sent them a photo (through their website) and they returned my inquiry with an approximate value. They may be able to tell you about the other ‘Lincoln’ hallmark/stamp. They were very friendly and helpful. Might give that a try.