Nakai is a Navajo name, so you can expect it was indeed Navajo made, either by an individual or a workshop employing Navajos.
The chip inlay style is a commercial project that got popularized in the 1960s. The point of it was to satisfy the newly-growing demand for Indian jewelry at the more affordable souvenir end. There was one high-end jeweler, Tommy Singer, who is credited with starting the style. So it's sometimes called "Singer style." Here, the turquoise and spiny oyster are remnants mixed into a bonding adhesive. The silver stamping on the cuff mostly likely was done by a machine process vs. hand applied.
The little ring is very sweet! I like the shaping of the stones. I'd guess Zuni made.