The annotations break down the scientific, optical, and physical details of the stone. Sunstone is a breathtaking variety of feldspar known for its internal fire, caused by light interacting with metallic inclusions. Using the sample in your image as a guide, we can explore every facet of its identity. It is a specific, sodium-calcium plagioclase feldspar. This makes Sunstone a relatively durable gemstone, suitable for pendants and earrings, but requiring care in daily-wear rings. Opaque to highly translucent. The finest stones (like yours) are remarkably clear, allowing the internal phenomenon to be seen with exceptional clarity. When light hits these internal metallic plates, they act as tiny mirrors, catching the light and reflecting a dynamic, sparkling fire. This effect is known as adventurescence. Sunstones are almost always cut as smooth, highly-polished Faceting is extremely difficult and rarely done, as it scatters the inclusions too much and makes the stone look less fiery. The cabochon shape concentrates the adventurescence into a single, moving patch of fire.A smooth, precisely shaped oval maximizes the concentrated pool of luster and maximizes the movement of the Schiller.