ColourPop 81 Points is a cool purple with a frost finish that is limited edition and retails for $4.50. In comparison, Natasha Denona Amethyst (141M) is a cool purple with a sparkle finish that is discontinued and retails for $29.00.
Natasha Denona Amethyst (141M) is 85% similar — it is more shimmery, darker, cooler.