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Sunstone vs Goldstone: Natural Feldspar or Furnace Glass?

By Digital Towns Crystals · Last reviewed October 8, 2026

Short answer: sunstone is a natural feldspar, Mohs 6 to 6.5, whose glitter comes from flat flakes of hematite or copper that grew inside the crystal. Goldstone is man-made glass in which copper crystals were grown on purpose during slow cooling, a technique developed in Murano, Venice, around 1600. Under a loupe goldstone shows countless tiny, evenly scattered triangular sparkles in otherwise clear glass; sunstone shows fewer, larger, flat platelets in a colored, translucent stone.

How is goldstone made?

The recipe is the whole story of goldstone, and it explains every clue a buyer can use. A review of aventurine glass by Laurent Cormier of Sorbonne Université dates its invention to Murano at the end of the 16th or early 17th century and describes the requirements as copper reduction, heat treatments and controlled atmospheres (Glass Europe). The Courtauld Institute's object study of a Venetian aventurine bowl spells out the steps (Courtauld):

  1. Copper oxide, a black powder, is added to the molten glass.
  2. A reducing atmosphere strips the oxygen, turning it into metallic copper. Glassmakers created it with smoke from burning wood or by adding iron, tin or antimony oxides, wrapped in small sachets called scartocci.
  3. The metallic copper precipitates as crystals that look triangular and hexagonal under a microscope.
  4. The glass is then cooled very slowly to room temperature. The Courtauld text notes that the hard part is not starting the crystals but enlarging and dispersing them during that slow cooling.

The process was so unreliable that its success was called an adventure, avventura in Italian, a possible source of the name aventurine. Cormier also notes that later makers developed chromium and iron versions alongside the copper type. Geology.com points out that the glass of reddish brown goldstone is itself colorless; the warm color is reflection from the copper crystals (Geology.com goldstone). So goldstone is not a stone that happens to resemble sunstone. It is a deliberate imitation of natural aventurescent stones, and an old one.

What is sunstone, by contrast?

Sunstone is a trade name for feldspar with a glittering optical effect. GIA explains that the name refers to the gem's appearance rather than its chemistry, and that both main branches of the feldspar family produce it: the potassium feldspar orthoclase and the plagioclase feldspars, which include oligoclase and labradorite (GIA). The glitter is called aventurescence, a sparkly, metallic-looking luster caused by flat, reflective inclusions. In sunstone those inclusions can be hematite, copper or another mineral.

Geology.com records that the first materials called sunstone were oligoclase. The best-known sources today are India, Norway, Tanzania and Oregon. Oregon material comes from basalt flows in Lake County and Harney County, where the feldspar grows as crystals in the lava, and Oregon has made sunstone its state gem (Minerals.net). The copper in Oregon stones was described in a 1985 Geology paper by Hofmeister and Rossman on the exsolution of metallic copper from Lake County labradorite, which the Cormier review cites. Our sunstone guide covers the varieties and the treated andesine story; the feldspar guide places sunstone in the larger family.

Sunstone and goldstone side by side

Feature Sunstone Goldstone
What it is Natural feldspar (oligoclase, labradorite, orthoclase) Manufactured glass
Where the sparkle comes from Flat hematite, copper or other platelets grown in the crystal Copper crystals grown in the melt during slow cooling
Body color Colorless, yellow, orange, red, pink, green Colorless glass; color comes from the crystals or added metals
Mohs hardness 6 to 6.5 Glass, roughly 5 to 6
Specific gravity 2.62 to 2.65 Varies by glass recipe
Refractive index 1.525 to 1.548 Varies by glass recipe
Cleavage Yes, feldspar cleavage None, conchoidal fracture
Colors available Mostly warm tones Reddish brown, blue, green, purple
Origin India, Norway, Tanzania, Oregon and others Glass factories, first in Murano

The sunstone hardness, gravity and optical figures are from Minerals.net. Goldstone has no fixed numbers because it is whatever glass the factory used.

How can you tell them apart?

Count and size the sparkles

Under a 10x loupe, goldstone shows a dense field of tiny, sharp, evenly sized points at every depth of the glass, all similar in size. Sunstone's platelets vary: Geology.com describes Tanzanian sunstone with very coarse inclusions, some over one millimeter in size, and other sunstone with only a reddish or golden sheen when the inclusions are small. If every sparkle is the same tiny size and they fill the stone uniformly, think glass.

Watch the flash as you rotate

In sunstone the platelets share a common orientation. Light reflects from them at a common angle, so a strong flash appears only at certain positions, as Geology.com explains. Goldstone's crystals are not aligned, so it twinkles at every angle and never produces one sudden sheet of reflected light.

Look at the body color between the sparkles

Find a gap between inclusions. Goldstone's base glass is clear, and the uniform brown glow disappears where there are no crystals. Sunstone has its own body color, often orange, peach or red, visible even where no flakes are present.

Check the color itself

Blue, green or purple glitter in a uniform, saturated base is goldstone; Geology.com notes those colors are made with compounds of metals other than copper. Natural sunstone is mostly yellow, orange, red and pink. Rare green Oregon stones exist, but they are faceted gems, not inexpensive glittering spheres.

Look for bubbles, slag and cleavage

Geology.com warns that a goldstone batch can contain areas with few crystals, areas with numerous gas bubbles and areas of slag. Round bubbles are a glass signature. Sunstone, as a feldspar, has cleavage: chipped edges on tumbled sunstone sometimes show small flat, stepped breaks, while goldstone chips into smooth curved shells.

Use the price and the form

Goldstone is made in large blocks, so it is sold cheaply as big uniform spheres, towers, hearts and beads. Sunstone tumbles are inexpensive too, but a large sphere of perfectly even, flawless glitter at a low price is almost certainly glass.

How do prices compare?

Goldstone is cheap and its price does not vary much with quality, because supply is unlimited. Sunstone covers a wide range. Geology.com notes that colorless and yellow stones are the least expensive and values rise through pink, orange and red, with bright red, green and bicolor stones at the top; nice orange cabochons can cost under $50, while bright red or bicolor faceted Oregon stones can exceed $1,000 per carat. Tumbled Indian sunstone, the kind most crystal buyers see, sits at the low end.

Which should you buy?

  • Buy sunstone if you want a natural mineral: a tumbled piece or palm stone for everyday handling, or an Oregon faceted gem for jewelry. Ask whether a red stone is Oregon material or treated andesine.
  • Buy goldstone if you want the look at a low price, the blue night-sky variety, or a piece of glassmaking history. It is a fine purchase when it is labeled as glass, as our glass imitations guide explains.
  • Do not pay sunstone prices for goldstone. Listings that call goldstone a natural stone or "monk's stone from the earth" are mislabeled.

In crystal traditions sunstone is associated with warmth, optimism and leadership, and goldstone with ambition; those are beliefs, not properties.

What to look for when you buy sunstone

Good sunstone listings name the feldspar type or locality and show the stone under direct light so the flakes are visible. For tumbles, look for orange to red body color with visible flakes rather than a dull brown stone. For contrast, keep a piece of labradorite, the plagioclase species that Oregon sunstone belongs to.

  • Sunstone: individual sunstone pieces, large enough to rotate under a lamp and see the platelets flash on and off.
  • Sunstone Tumbles: inexpensive tumbled sunstone, the right size for the loupe check on body color and flake size.
  • Labradorite: high-flash labradorite, a plagioclase feldspar related to Oregon sunstone, useful for comparing feldspar's oriented reflections with goldstone's even glitter.

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Frequently asked questions

Is goldstone a real stone?

Goldstone is real glass, not a natural stone. It is made by growing copper crystals in molten glass under reducing conditions and cooling it slowly, a technique invented in Murano, Venice, around 1600. It is a legitimate decorative material when it is sold as glass.

Is goldstone the same as sunstone?

No. Sunstone is a natural feldspar with mineral platelets inside; goldstone is manufactured glass with copper crystals. They look similar because both glitter, an effect called aventurescence, which is why goldstone was historically sold as aventurine glass.

How can you tell sunstone from goldstone at home?

Use a loupe and a lamp. Goldstone shows countless tiny, uniform sparkles in clear glass and twinkles at every angle. Sunstone shows fewer, larger and less uniform flakes in a colored stone, and its flash appears strongly at particular angles.

Is blue goldstone natural?

No. Blue goldstone is manufactured glass colored with compounds of a metal other than copper. There is no natural blue sunstone that looks like it. It is often sold under fanciful names, but every blue glittering sphere of this kind is glass.

Is sunstone treated?

Most tumbled sunstone is untreated. The exception is red andesine marketed as Tibetan or Mongolian sunstone in the 2000s, which labs found had been colored by copper diffusion. Oregon sunstone is sold as natural and untreated.

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