Loose Sunstone Gems for sale. Faceted and cabochon sunstone. Star Sunstone. Oregon Sunstone. Sunstone gem is a plagioclase feldspar, has a hardness of between 6 - 6.5, the Sunstone can be found in red, orange, yellow , green, colorless color. We can find : opaque , translucent or transparent (depending on its inclusions). Opaque material is cut as cabochons and transparent material is cut faceted. Some cabochons display a star effect (Star Sunstone). As for its inclusions, it is normal to find thin copper plates , hematite or goethite which are aligned and producing aventurescence (metallic effect produced by the reflection of light).