Featured Identify this Navajo or Zuni "J" Silversmith?

This very plain mark is on the back of a sterling silver Bolo (String) Tie.
I'm pretty sure this is of Navajo or Zuni origin, but I'd like to do better than that!
I have a resource that shows a couple of similar marks, but the "STERLING" font is different...
Also, I'd say the inlaid stones are turquoise and red coral (? - not sure, with this grain in it), and I guess the black would be onyx, but what would the purple bars be?
Thanx in advance...

 

Hard to tell from the photos,but it could be Sugilite.

 

Red material may be spiny oyster not coral but I’m not very knowledgeable about NA jewellery.

 

I'm not, either, but I believe you are right! I found examples of Navajo using spiny oyster in jewelry, and it looks spot on.

 

Here's a closer look at the stones:

 

might check James Livingston Navajo

 

There is also a Jason Livingston, Navajo who made inlay pieces.It's just another guessing game of who made me.

 

The edges look Navajo but the inlay looks Zuni, so.... I'd say spiny oyster shell, sugilite and some really funky turquoise. No idea whodunnit.

 

It has a Navajo look. They have been making channel work for a long time, although it started among the Zuni.

I agree, the orangy red is spiny oyster, the purple is most likely sugilte, which the Navajo have been using for the last few decades.

The J is just one of the many Navajo who can't be bothered to mark a bit extra.
Almost entire families use the J mark, including many of the Jacksons and some members of the James family. A small clue can be the style of the sterling mark and the position in relation to the J. But I am sure many use that exact combination as well.