Help identifying mark on squash blossom necklace

Hello, and thank you to anyone who responds. I would be very interested in learning more about the marks shown on this necklace and drawn on paper in the attached photo. Thank you in advance for sharing your knowledge.
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Hi I have a neckalce very similar to yours. The mark on the back is like a Roman number VI. I am also trying to find our information on this. Have you found any info on yours yet?

Hello,

Can you please give us a larger image of the mark. When I enhance the signature it becomes very blurry. Thank you.

No, but I just got another reference book and will see if I find it there.

I put a drawing of the mark below the necklace because it was so hard to photograph. The drawing is exactly like the mark. Thank you for taking the time to look at it.

Hello,

The mark is made by an electric engraver. During the 1960s up until the early 1990s we made jewelry in-house and would use a double TT mark for Tobe Turpen Trading. However, the use of the stamp really wasn’t used consistently until the late 70s when buyers started demanding a hallmark. From what I can see of your necklace it appears to have some age, possibly from the 60s or older. I imagine a piece like this could have been made in a setting like Tobe Turpens. It has very nice matched turquoise, possibly from a trader. After it was made Navaho was written on the back with what could be a code of how much the piece cost. It doesn’t seem to be initials and doesn’t make a recognizable symbol.

Thank you Jason. It is very helpful that you are sharing your experience. Your theory about this signature makes a lot of sense. The fact that it says “Navaho” seems to indicate that it was Native-made but not connected to a specific artisan and perhaps from a group of artisans. Thank you again.
Lynn