Vintage Native Opal Mosaic Sterling Brooch Marked FJC

Wonderful vintage brooch is a multi-colored opal mosaic in sterling silver. Looks like a Native American piece to me. It's signed FJC on back and is in great vintage condition with just some tarnish, no real issues. I'm not sure how these are made, but looking from the side, I can see a thin layer of pink under the opal layer, which might be what gives some of the sections a purple or pink tint. 1 1/2" x 1 1/4".