Vtg scalloped gold rainbow rhinestone black pin

This is a very large and interesting intake pin consisting of a large black glass cab stone in the center surrounded by large assorted pastel rhinestones in multi colors, the pin itself is a gold scalloped circle that is larger on the bottom like a shell. There is what I think might be a makers mark but too small for me to read. Very unusual in excellent condition. 2.5” x 2.25”