Amethyst rondelle faceted 5mm. The February birthstone, Amethyst is one of the most popular of the colored stones as it is believed to bring peace of mind to the wearer. Just like any other quartz color varies from light to dark shade of purple. Amethyst works well with citrine or yellow color with similar finish. Amethyst also works with lapis or any blue shade crystals combined with silver spacers.