Sunstone Quality Factors


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This 11 ct. bicolour sunstone is highly desirable for its colour alone. An attractive display of aventurescence and a unique cut make it even more valuable. – Robert Weldon
Colour
Most sunstones have yellow, orange or brown bodycolour. Green is extremely rare. Small inclusions create a reddish or golden sheen on top of any body colour, while larger inclusions create attractive, glittery reflections. Sunstone inclusions can be hematite, copper, or some other mineral.

The 2.40 ct. faceted bicolour gem displays an unusual green and yellow combination. Gem cutters seek ways to display unusual colours from rough like the 9.36 ct. specimen. – Robert Weldon
These fine-quality gems display some of the sunstone colours found in the Plush, Oregon, mining area. – Jeff Scovil, courtesy Jeff Scovil
Oregon sunstone is a transparent feldspar with copper inclusions. It comes colourless as well as in a wide variety of colours, including pale yellow, pink with brilliant aventurescence, orange, red, green, and blue-green. The red version is often marketed as “spinel red,” and its vivid hue - if not its hardness - rivals spinel or even ruby.

Deep red sunstone from the Ponderosa mine is marketed as spinel red. Although it’s not as hard as spinel or ruby, this sunstone type has a vivid scarlet hue that can be equally lovely. – Bart Curren
Some Oregon sunstones are either bicoloured or tricoloured, and a rare few display colour change. Currently, the top deep green, deep red, and intensely bicoloured sunstones are considered extra fine.

Some sunstones are bicoloured, which makes them ideal for free-style designer cuts
(bottom). They might also be tricoloured, like this lovely 32.80-ct. Oregon sunstone (top).
The cut is a spectacular example of the sculptor’s artistry. – Tino Hammid (bottom); Maha
Tannous, courtesy Dust Devil Mining Company, Beaver, Oregon (top)
Cut
Sunstone is available in a wide range of shapes and sizes, from exquisite fantasy cuts for designer jewellery to precise calibre cuts for manufacturers.

This “Dreamscape” fantasy-cut sunstone was created by gem designer John Dyer. – Lydia Dyer, Gem courtesy of John Dyer & Co.
Calibre-cut sunstones are available for mass-market production or custom jewellery designs. – Valerie Power, courtesy Desert Sun Mining & Gem Co., Inc.
Clarity
All Oregon sunstones have an extra sheen that’s caused by copper inclusions. The sheen is there even if the inclusions aren’t large enough to create actual aventurescence.

A photomicrograph shows inclusions in a gem from Oregon’s Ponderosa Mine, magnified 12 times. – Shane F. McClure, courtesy Dr E. J. Gübelin Collection

These oligoclase sunstone cabochons display an attractive adventurescent sparkle. – Edward Gubelin, courtesy Dr Edward J. Gübelin Collection
Carat Weight
Sunstone can be found in relatively large sizes, but most calibre-cut stones weigh one carat or less.

The unusual size of this 146.07 ct. oligoclase sunstone dwarfs the sunstones, moonstones and other gems in the background. – Terri Weimer, courtesy Blue Moon Enterprise