Madagascan Sunstone are rare gemstones with a beautiful glittering sunlight effect. Named for its country, Madagascan Sunstone’s attractive reddish-oranges in combination with its signature glittering reflections and sheen make it a timeless addition to any jewelry collection.
Hardness 6 - 6.5
Refractive Index 1.510 - 1.550
Relative Density 2.62 - 2.65
Named for its resemblance to the sun, Sunstone’s most important attribute is aventurescence (schiller), the beautiful glittering sunlight effect caused by light bouncing off tiny reflective metallic inclusions of copper, goethite or hematite within the gem. Aventurescence originated in an 18th century Venetian glassworks, when copper filings accidentally fell into a batch of molten glass. According to legend, the workers exclaimed, “a ventura”, which means ‘by chance’.
The appearance of aventurescence depends on the size of the inclusions; small inclusions create a reddish-golden sheen on the gems’ body color, while larger inclusions create the gems’ signature glittering reflections.
Translucent to semi-translucent, Madagascan Sunstone’s key quality considerations are the brilliance and conspicuousness of its attractive metallic reddish-orange schiller, as well as optimal lapidary. Madagascan Sunstone is cut as cabochons (cut in convex form and highly polished, but not faceted) with an excellent finish, proportion and shape.
Considering its name, it’s not surprising that legend also connects Sunstone to the sun. According to one story, Pope Clement VII (1478-1534) possessed a Sunstone with a golden spot which moved across the gem in motion with the sun. Native Americans used Sunstone in ‘medicine wheel’ ceremonies to connect with the healing light of the sun, while in India it was once believed Sunstone brought good health, insight, power, and prosperity. Sunstone was also once coveted for its purported ability to guide its wearer through the journey of life.
Usually brown, colorless, green, greenish-blue, multi-color, orange, pink, red, and yellow, Sunstone is a member of the plagioclase Feldspar group and is closely related to Labradorite and Moonstone. Also called Aventurine Feldspar, ‘Sunstone’ typically refers to the gems’ appearance rather than its composition or structure. Feldspar (derived from the German ‘feldt spat’, meaning ‘field stone’ because of its ability to enrich the soil with plant nutrients) is a mineral family especially known for gems with beautiful optical phenomenon, such as adularescence, aventurescence and iridescence. Its two subgroups are the plagioclase group and the potassium group. Distinguished by their calcium and sodium content and ratio, the plagioclase group includes most gem varieties. Gems in the potassium group share the same chemical composition, but are distinguished by their crystal structure. As many Feldspar gems look alike, some are often confused due to their similar compositions and trade names.
Sunstone is an exotic gemstone whose prices vary widely according to availability and quality. Always scarce, especially in its fine qualities, Sunstone is one of the most coveted varieties of Feldspar. Sunstone is predominately mined in India, Madagascar, Tanzania, and the USA (Oregon Sunstone has been the State of Oregon’s official gemstone since 1987).
Madagascan Sunstone is mined from a ravine that separates Mount Tsiafakafo from Mount Tsiafakafokely in the Ankaratra Mountains of Madagascar’s Antananarivo Province. First reported in 1922, this area is known as ‘Madagasikara’ in a local dialect.
Madagascan Sunstone is also a totally natural gemstone and not enhanced.
Durability & Care
A relatively durable jewelry gemstone, Madagascan Sunstone (Mohs’ Hardness: 6 – 6.5) should always be stored carefully to avoid scuffs and scratches. Clean with gentle soap and lukewarm water, scrubbing behind the gem with a very soft toothbrush as necessary. After cleaning, pat dry with a soft towel or chamois cloth.