Rainbow Moonstone

Rainbow moonstone is a near-colorless to milky-white feldspar prized for a floating blue-to-multicolored sheen. Despite the name, gemologically it is usually a transparent variety of labradorite (a plagioclase feldspar), not the orthoclase that forms classic moonstone.

Its shimmering glow comes from adularescence and labradorescence, optical effects caused by light scattering off microscopic intergrown layers within the feldspar. The best stones show a strong blue sheen plus flashes of green, gold, peach, and violet against a clear or white body.

Clean, transparent material with strong flash is the most valued, and the stone is widely used in bohemian and contemporary jewelry.

Rainbow moonstone forms in igneous rocks, particularly slowly cooled intrusive bodies, where plagioclase feldspar crystallizes and then, on cooling, separates into ultra-thin alternating lamellae of slightly different composition (exsolution).

These microscopic layers scatter and interfere with incoming light to produce the blue adularescence and multicolored labradorescence. The effect depends on the thickness and orientation of the layers, so cutters orient cabochons to maximize the sheen.

The primary source of fine rainbow moonstone is India, with additional material from Madagascar and Sri Lanka.

Look for a transparent to milky, colorless or white stone displaying a billowy blue sheen and rainbow flashes that shift as the stone is tilted. Hardness is 6-6.5, luster vitreous, streak white, and feldspar's two directions of cleavage are present.

The adularescent/labradorescent sheen and feldspar cleavage are key identifiers. Compared with classic white moonstone (orthoclase), rainbow moonstone is more transparent and shows multicolor flash rather than a simple white-blue glow.

Distinguish it from opal (play-of-color from a different structure, lower hardness) and from milky quartz or chalcedony (no cleavage, no directional sheen). Glass imitations lack true cleavage and directional adularescence.

Rainbow moonstone is exclusively a gemstone, cut into cabochons, beads, and faceted pieces for rings, pendants, and earrings. Cutters orient cabochons to center the blue and rainbow flash, which drives value.

Its ethereal sheen makes it popular in both fine and bohemian-style jewelry, set in silver and gold. Its moderate hardness and cleavage call for protective settings and gentle care in rings.

Metaphysically, rainbow moonstone is associated with intuition, emotional balance, new beginnings, and feminine energy, often linked to the moon. These attributes are spiritual beliefs and not scientifically supported.