Sunstone: The Complete Guide

Sunstone is a gem of fire and sparkle. Its defining characteristic — aventurescence, the shimmering metallic glitter from reflective mineral platelets within the stone — creates a visual effect of sparkling, moving light that is genuinely captivating. The finest sunstone, from Oregon, adds to this base effect a range of body colours from champagne to coral to vivid copper-red-green that makes it among the most distinctive and striking gems available. Oregon sunstone is also one of the few commercially significant gem deposits in the continental United States.

What Sunstone Is

Sunstone is a variety of feldspar (typically oligoclase or labradorite) that contains tiny, oriented platelets of a reflective mineral that create aventurescence — the sparkling, metallic shimmer that gives the stone its name. In European sunstone (from Norway, India), the platelets are typically hematite or goethite (iron oxides). In Oregon sunstone, the platelets are native copper — an unusual occurrence that contributes to the stone’s distinctive colour range.

Feldspar sunstone has a Mohs hardness of 6-6.5 and two cleavage directions, making it moderately durable. It is suitable for all jewellery applications with normal care, though ring settings should offer some protection. The feldspar composition means care should be taken with acidic cleaning solutions.

Oregon Sunstone: The American Gem

Oregon sunstone from the Harney County deposits in southeastern Oregon is unique in the gem world. The copper platelets that create its aventurescence can be present in such density that the copper itself influences the body colour of the stone — creating pink, salmon, red, and bicolour green-red and green-copper specimens that are unlike any other sunstone. The deep copper-red “schiller” (the term for the aventurescence effect in feldspar) in fine Oregon sunstone creates a fiery, metallic warmth of extraordinary visual impact.

Oregon sunstone is mined at several sites in Harney County, with the Dust Devil mine and Ponderosa mine being among the best-known. The deposits occur in volcanic basaltic lavas, where the sunstone crystals grew as phenocrysts (large crystals in the lava matrix). Mining is relatively accessible — Oregon sunstone mining has an active recreational and small-scale commercial community — and the gem has developed a strong following in American artisan jewellery.

Oregon Sunstone Colours

Colourless to pale yellow: lowest commercial value, still shows aventurescence

Yellow to champagne: attractive with good schiller, accessible price range

Peach to salmon pink: increasingly desirable, moderate value

Deep orange-red: the most prized colour, strong schiller, premium value

Bicolour (green and red/copper): extraordinary and rare, collector premium

Green: rare, caused by differential copper absorption, strong collector interest

Indian and Norwegian Sunstone

Indian sunstone from Rajasthan shows strong aventurescence (typically orange-red) from hematite platelets in an oligoclase matrix. It is widely available commercially at accessible prices and is the sunstone most commonly seen in volume commercial jewellery. Norwegian sunstone from Tvedestrand is historically significant but production is limited today. The aventurescence in Indian material can be impressive; it lacks the body colour variety of Oregon sunstone but delivers good visual impact at low cost.