Buckle w/ engraved (not stamped) signature...

[omdroparebop]

Hello folks. Greetings and thanks in advance to the forum. I hope that one of you knowledgeable folks might help me discover the name of the artist that crafted this buckle.
It is either Navajo or Zuni. I was lucky enough to pick this up as old pawn, on a trip to Scottsdale last week. The seller indicated that it was from an estate; that the rest of the collection dated to the 70s; and that the piece stylistically was consistent with a 70s time frame.
Neither she nor I were able to recognize the engraved cursive signature on the back.
The top word is "Sterling." The bottom line (apparently the smith's signature) is indecipherable to me.
Whomever the artist was, he signs his name like a doctor. If this forum fails to come up with an answer, perhaps I can find a pharmacist to decrypt it for me. :)
Here are the clues:

[ValkyrieVixen]

That's a tough one. My first thought is Hopi, due to the overlay design with a textured background.
There are some Navajo artisans who do similar work too though.
The mark kind of looks like R. Q??? so I searched Q names but almost all were Zuni.
It's a stunner but I'm stumped.

[omdroparebop]

Someone else told me it looked like a "Q".
There's a Raymond Quam; who I believe is Zuni.
What I've seen of his work doesn't look a bit like this, though.
Very nice of you to take a look. I appreciate it.

My best guess was that the last name began with a P; but it's a tough one to make out.