Multicolor Tourmaline

Multicolor tourmaline refers to elbaite crystals that show two or more distinct colors within a single stone, a phenomenon tourmaline is uniquely famous for. Two-color stones are called bicolor and three-color stones tricolor.

Colors can be arranged lengthwise along the crystal or as concentric zones across it. The best known example is watermelon tourmaline, with a pink center surrounded by a green rind, mimicking the fruit.

Lapidaries often cut multicolor crystals to preserve the color boundaries, making each gem a one-of-a-kind display of natural color zoning.

These crystals form in granitic pegmatites, where tourmaline grows over a long period from evolving boron- and lithium-rich fluids. As the chemistry of the growth fluid changes, the trace elements coloring the tourmaline (manganese for pink, iron for green, and others) change too, producing color zones.

Lengthwise color changes record how conditions shifted as the crystal grew taller, while concentric zones reflect changes outward from the core.

Classic sources include Brazil, Afghanistan, Pakistan, Nigeria, Madagascar, Mozambique and Maine and California in the United States.

Look for the standard tourmaline habit: elongate, striated prismatic crystals with rounded triangular cross-sections, hardness 7-7.5, vitreous luster and no cleavage.

The diagnostic feature is obvious: two or more colors within one transparent crystal, sharply zoned along the length or in concentric bands. Watermelon stones show a pink core ringed by green.

Because the color zoning is a natural growth feature unique among common gems, it readily distinguishes multicolor tourmaline from single-color gems and from assembled or dyed imitations, which lack the smooth natural color gradients.

Multicolor tourmaline is highly prized in jewelry and among collectors precisely because each stone is unique. Watermelon slices are popular as pendants, and bicolor stones are set to showcase their color contrast.

Well-defined, eye-clean stones with sharp color boundaries command premium prices. Crystal slices and specimens are also collected for their natural beauty.

Metaphysically, multicolor and watermelon tourmaline are associated with balance and the heart, claims that are traditional rather than scientifically demonstrated.