Please help identify silver ring

I am hoping that someone can help identify the initials on this ring, or perhaps provide a background of where this came from. It was given to my stepfather by my maternal grandmother. I don’t know where she got it or if it was in the family before that. It is silver with a black onyx stone. There are feathers with ornate details. Engraved on the finger side of the ring is “F G”, and it seems to be similar to other Native American rings. Thoughts? Any help is very much appreciated!

<img src=/uploads/db1846/original/2X/b/bf3ce260ba27cdce3536a16d2f7ff47334b9ba5e.jpg">

<img src=/uploads/db1846/original/2X/1/1e5a2f71ace4ac8c2fb5be41ef75457349f800a9.jpg">

<img src=/uploads/db1846/original/2X/a/abba8488cf7f82833f7a49ba42e914adb46ee961.jpg">

Hi, jif – I’m pretty sure it’s the mark of Fred Guerro Jr., a Navajo artist active since the 1990s, according to Bille Hougart’s book, Native American and Southwestern Silver Hallmarks. There’s a faint “R” to the right of the FG, which makes it Junior’s. His father (also Fred Guerro) also used FG as his mark. cheers, Martha T.

Thank you, Martha!