Vintage amethyst and diamond ring, 14k white gold filigree

14k white gold filigree ring with amethyst and diamonds.  It measures over 1/2" long, it's a size 5 1/2 and can be sized.  The cut of the amethyst is interesting.  It's faceted on the bottom, smooth cabochon cut on the top.  It's called a buff top.  Excellent condition, circa 1920.