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Labradorite vs Moonstone: Two Feldspars, Two Kinds of Light

By Digital Towns Crystals · Last reviewed October 8, 2026

Short answer: put each stone under one lamp and rock it. Labradorite throws a saturated sheet of blue, green, gold or orange off a gray to black body, and the color switches off sharply at other angles. Moonstone shows a soft, whitish to blue glow that floats just under the surface of a pale or colorless body. The confusing case is "rainbow moonstone": GIA classes it as labradorite, so a rainbow piece is labradorite whatever the tag says.

Is rainbow moonstone labradorite or moonstone?

It is labradorite. GIA's moonstone description says plainly that a variety of labradorite is sometimes called rainbow moonstone, and that the light-bodied Madagascar material sold under that name is labradorite rather than orthoclase. The trade keeps the name because, as the same page puts it, a stone's appeal as moonstone has more to do with its glow than its mineral identity.

That is the one fact buyers most need, and the reason this comparison exists. A strand labeled "rainbow moonstone" is not fake. It is a natural feldspar with a misleading trade name. Problems start only when a seller prices rainbow material as if it were fine blue-sheen moonstone, or describes a dark, flashy labradorite palm stone as moonstone.

The two minerals sit on different branches of the feldspar family. GIA classes moonstone as a variety of orthoclase, the potassium feldspar, while labradorite is a plagioclase, a sodium and calcium feldspar. Our feldspar overview maps the whole family.

Labradorite and moonstone, property by property

Property Labradorite Moonstone
Feldspar branch Plagioclase (Na, Ca) Alkali feldspar, orthoclase with albite
Crystal system Triclinic Monoclinic (orthoclase host)
Mohs hardness 6 to 6.5 6 to 6.5
Specific gravity 2.69 to 2.72 About 2.58
Refractive index 1.560 to 1.568 1.518 to 1.526
Cleavage angle About 86 or 94 degrees 90 degrees
Typical body color Gray to nearly black; clear in rainbow material Colorless, white, peach, gray, green
Optical effect Labradorescence: saturated, angle-specific color Adularescence: soft, billowing white to blue

Numbers come from Minerals.net on labradorite, GIA's moonstone overview and Geology.com on orthoclase. The density gap is small but real: labradorite is roughly 4 percent heavier than moonstone of the same size, which only a careful hydrostatic weighing will show.

Why does one flash and the other glow?

Both effects come from the same kind of event. A feldspar that was one uniform mix at high temperature separates, while cooling in the solid state, into stacked sheets of two slightly different compositions. What differs is how regular those sheets are, and that decides whether light comes back as a color or as a haze.

The regular layers in labradorite

GIA's 2025 review of phenomenal gems describes the labradorite structure, called the Bøggild intergrowth, as alternating wider calcic lamellae of roughly 70 to 200 nanometers and thinner sodic lamellae of roughly 50 to 100 nanometers (GIA, A Review of Phenomenal Gemstones). Because the spacing is so regular, the layers reinforce one narrow band of wavelengths. A combined pair thickness near 150 nanometers gives blue, and above 250 nanometers gives red, with the rest of the spectrum in between. The same review notes the color shows on the (010) cleavage surface, which is why cutters orient labradorite so carefully. Webmineral puts it the same way: the color is due to optical interference on Bøggild exsolution lamellae.

The irregular layers in moonstone

GIA states that only cryptoperthite, an alkali feldspar with nonperiodic submicron intergrowths of albite and orthoclase, can produce the desaturated glow that earns the moonstone name. Irregular spacing means many wavelengths are scattered at once, and the eye reads that mix as white or pale blue. GIA's encyclopedia puts the layer scale at about 0.5 micron, close to a wavelength of light.

Why rainbow material looks like moonstone

The review explains the trade name too. Finnish labradorite with a nearly black body shows its color right at the surface, while "rainbow moonstone" labradorite, almost free of iron oxide inclusions, shows diffuse iridescence coming from deeper inside the crystal. That depth softens the flash into something moonlike, but the color is still the saturated spectral kind. The iridescence guide covers thin-film optics in more depth.

Five tests you can do at a table

You need one small flashlight, a dark room, a 10x loupe and, for the last test, a kitchen scale that reads to 0.1 gram.

  1. Body color with the effect off. Tilt the stone until the color disappears. A gray to charcoal body points to ordinary labradorite. A colorless or pale body with no sheen narrows it to moonstone or rainbow labradorite, so go on to test 2.
  2. What color is the light? Moonstone's sheen is white, silvery or blue. Any yellow, orange, green or purple flash, or several colors side by side, is labradorite. Peach and gray moonstones still glow white or blue over their body color.
  3. How wide is the angle? Labradorite's flash is tightly directional; a few degrees of tilt kill it. Moonstone's glow rolls across the dome over a wider arc, and GIA's quality notes mark down moonstone whose glow is only visible within a restricted viewing range.
  4. Look for stripes. Under the loupe, labradorite often shows straight parallel bands of different color, the edges of twin lamellae. Geology.com's labradorite article points out the parallel lines in strongly twinned tumbled stones from Madagascar. Moonstone more often shows small "centipede" tension cracks.
  5. Specific gravity. For a piece of 20 grams or more, weigh it dry, then weigh it hanging in water and divide dry weight by the loss. Results near 2.58 point to moonstone, near 2.70 to labradorite. The specific gravity guide walks through the method.

A gemologist would add the refractometer: the two index ranges, 1.518 to 1.526 for moonstone and 1.560 to 1.568 for labradorite, do not overlap, so one reading on a flat polished face settles a cut stone.

Where is each one mined?

Labradorite takes its name from Labrador. Geology.com records that it was discovered on the Isle of Paul near Nain in 1770 by a Moravian missionary. Finland produces the most saturated material, and the name spectrolite was given to the best of it by the director of the Geological Survey of Finland; today that word is stretched to cover bright labradorite from anywhere. Madagascar and Russia supply much of the gray to black commercial rough, and India produces small amounts of transparent material with an internal flash. The International Gem Society adds that a labradorite moonstone with a blue sheen is known from Madagascar, with a specific gravity of 2.70.

Moonstone comes mostly from gem gravels. Geology.com calls Sri Lanka the world's most important source of fine moonstone and lists Brazil, Myanmar and India as significant producers, nearly all of it dug by small-scale miners rather than mechanized operations (Geology.com, moonstone). India supplies the peach, gray and green bodies; GIA notes that in 1997 miners in southern India found a bright "parrot green" moonstone.

How do prices compare?

Ordinary flashy labradorite is one of the cheapest phenomenal stones you can buy, because the rock is abundant and large pieces cut well. Price climbs with the share of the face that lights up and with rarer colors such as gold, orange and purple. Truly fine Finnish spectrolite is scarce.

Moonstone runs the other way. Common white and peach material is inexpensive, but GIA's quality guide describes the top grade as glassy, nearly colorless and carrying a mobile electric blue sheen, and it notes that large fine moonstone is very rare. A clean blue-sheen Sri Lankan cabochon can cost far more per carat than a labradorite of any size.

Two traps sit between them. Rainbow labradorite occasionally gets priced as blue moonstone, and Geology.com describes quartz-moonstone doublets, made by gluing a slab of quartz over a thin slice of blue flash moonstone. A doublet shows a flat seam line around the girdle under a loupe.

Which should you buy for what?

For a display piece, a sphere or a palm stone that performs across a room, labradorite wins: big, bold color for the money. For a ring or pendant with a quiet, luminous look, moonstone is the classic choice. Both are 6 to 6.5 on the Mohs scale with two good cleavages, so either one can split if knocked; Geology.com warns that one impact against a hard object can cleave a moonstone in two.

In crystal traditions, moonstone is associated with the moon and with June, and labradorite with change and intuition. These are customs, not mineral properties, and they should not change what you pay.

What to look for when you buy labradorite or moonstone

Ask for a video or two photos: one with the effect on, one with it off. That pair tells you the body color, the color of the light and how much of the face it covers, which together identify the stone and drive the price. For moonstone, the glow should sit centered on the dome. For labradorite, look for straight cracks running along the flash, which are cleavage fractures rather than twin lines.

  • Rainbow Moonstone Sphere: rainbow material in sphere form, a good way to see the deep, soft flash GIA attributes to nearly inclusion-free labradorite.
  • Peach Moonstone Sphere: true alkali feldspar moonstone with a peach body; turn it under one light and the glow stays white over the warm color.
  • Moonstone Tumbles: inexpensive tumbled moonstone for running the angle and body color tests side by side with labradorite.
  • Labradorite freeform with blue flash, Madagascar: a classic gray-bodied Madagascar piece with the strongly directional blue labradorescence.
  • Rainbow labradorite specimen, 1.60 lb, Madagascar: a 726 gram piece sold as spectrolite; a large face makes it easy to see twin stripes and color zoning. Treat "spectrolite" here as a quality word, since the name began with Finnish material.

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Frequently asked questions

Is rainbow moonstone real moonstone?

Not mineralogically. GIA identifies rainbow moonstone as a variety of labradorite, a plagioclase feldspar, while true moonstone is an alkali feldspar of orthoclase and albite. Rainbow moonstone is still a natural stone and an attractive one; the name simply follows the glow rather than the mineral, and a good seller says so.

Which is more valuable, labradorite or moonstone?

At the top end, moonstone. Fine colorless moonstone with a centered electric blue sheen, especially in larger sizes, is rare and priced per carat. Most labradorite is inexpensive because the rock is plentiful, although saturated Finnish spectrolite and pieces with full-face gold or purple flash command a premium.

Can moonstone flash blue like labradorite?

It can show blue, but differently. Blue-sheen moonstone glows as a soft, floating haze that moves smoothly across the dome. Labradorite's blue is a saturated sheet of color that appears and vanishes over a few degrees of tilt and often sits beside green or gold zones in the same stone.

Is black moonstone labradorite?

Not necessarily. Moonstone can have gray to nearly black bodies, and GIA lists gray to nearly black among its body colors. If the dark stone shows only a white to silvery glow, moonstone is plausible. If it flashes blue, green or gold in sharp patches, it behaves like labradorite and is worth asking about.

Are labradorite and moonstone durable enough for rings?

Both rate 6 to 6.5 on the Mohs scale and have two directions of good cleavage, so a hard knock can chip or split either one. Pendants and earrings are safer. For a ring, choose a protective bezel setting and take it off for gardening, gym work and housework.

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