This dazzling material was most likely mined in India. I have also seen lace amethyst from a claim near Wickenburg, Arizona. However, the Arizona material I saw had more of a dull coloring and the crystal structure was much smaller.
Lace amethyst shares the purple coloring of gem-grade amethyst but is embedded within an agate matrix. There are adjacent bands of white and pink agate which makes for unique and striking patterns for cabochons. The challenge in cutting is the varying hardness and potential fracturing of the amethyst crystal.