Rainbow Tourmaline

Rainbow tourmaline is a multicolored variety of tourmaline, usually elbaite (and sometimes the calcium-rich species liddicoatite), that displays many color zones in a single crystal. Sliced perpendicular to the crystal length, these stones can reveal stunning concentric, triangular, or star-like color patterns.

The term overlaps with watermelon, bicolor, and parti-color tourmaline but generally implies an especially rich, multi-banded display. The colors arise from changing trace-element chemistry during growth.

These vivid, naturally patterned stones are popular both as cut gems and as polished crystal slices.

Rainbow tourmaline forms in granitic pegmatites, where late-stage fluids carrying lithium, boron, calcium, manganese, iron, and other elements crystallize colorful tourmaline. As the composition of these fluids shifts repeatedly during growth, the crystal records each change as a new color zone.

In liddicoatite especially, the trigonal symmetry produces striking triangular and concentric color patterns visible in cross-section slices. Madagascar is the classic source of richly patterned multicolor and liddicoatite tourmaline; Brazil, Afghanistan, and Nigeria also produce rainbow material.

The number and sharpness of color zones reflect how many times and how abruptly the fluid chemistry changed.

Look for a tourmaline crystal or slice showing multiple natural color zones, with the characteristic rounded triangular cross-section and lengthwise striations. Hardness is 7-7.5, luster vitreous, streak white.

Sliced cross-sections often reveal concentric or triangular color patterns that are essentially impossible to fake convincingly, confirming natural tourmaline. Strong pleochroism and double refraction support the identification.

Distinguish from dyed or assembled imitations by the continuous, three-dimensional nature of the zoning and the genuine tourmaline crystal structure.

Rainbow tourmaline is prized as faceted gems, cabochons, and especially as polished crystal slices that display dramatic multicolor patterns. Slices are popular as pendants and collector pieces, with each one unique.

Value depends on the vividness, contrast, and symmetry of the color zones, plus clarity and size. Liddicoatite slices with crisp triangular patterns are especially sought after.

Metaphysically, rainbow tourmaline is said to combine the energies of all its colors for balance, though such claims are not scientifically supported.