Plume agate is a variety of chalcedony (a microcrystalline quartz) known for its beautiful, feathery or flower-like inclusions, called "plumes," that look like smoke, moss, or plants suspended in a translucent stone, often red, brown, white, or purple. Formed from silica-rich hydrothermal deposits, it's prized by lapidaries and collectors. This stone is a doublet comprising of 100% natural white plume agate (on top) cemented to Aurora Effect blue resin (bottom) to give it this gemstone a "sky" effect. Absolutely beautiful!