Sunstone is a bright orange feldspar gemstone. And like most feldspars it displays on the surface of the gem. In this instance it's a brilliant, spangled effect. The optical effect of sunstone is called a "shiller" or "aventurescence". This phenomenon is caused by the presence of reflective inclusions, such as hematite or goethite, that create a sparkling effect.
Deposits of this gemstone have been found in India, Norway, Canada, Russia, and the United States.
On a more spiritual or metaphysical level, sunstone can be used to encourage independence and originality. It's also said to encourage good luck in games.
Another beautiful and underrated gemstone.