Vintage Gold Plated Sterling Silver Enamel Ring Set, Stackable Rings, Gold-Tone Enamel Band Ring, Size 6.5 US

We have three super cool and unique stackable gold-toned enamel rings. Each ring features delicate enamel work. The thinnest and simplest of the three features turquoise and rust colored alternating rectangles bordered on all four sides by the gold toned ring band. The next features turquoise, rust, and navy blue colored rectangles of two different sizes, these alternate along with gold rectangles "unfilled" by enamel. And the last ring features thin navy blue rectangular patches that border longer patches of turquoise enamel sitting beneath a rust colored squiggle shape.
All three rings have been stamped 'U.S.A,' 'MMA,' and '6.' We were unable to find anything about the production of these pieces. Despite being marked 6, they fall more in the 6.5 category on a mandrill. The rings are in good vintage condition with minor tarnishing and wear to the gold plating.

Condition: Good condition with minimal wear and discoloration.
Ring size: 6.5 US
Weight: 5.6 grams