Few crystals are as instantly recognisable as watermelon tourmaline. Slice one and you'll see exactly why: a pink core surrounded by a green rind, sometimes with a thin colourless layer in between, the same colour pattern as the fruit it's named after.
Tourmaline is a boron silicate mineral that grows in long, prismatic crystals, and its colour comes from trace elements picked up while it forms. As a crystal grows, the chemistry of the fluid around it can shift, manganese produces the pink and red end of the spectrum, while iron and other trace elements produce green and blue. When that shift happens partway through growth, the crystal ends up banded rather than a single colour, and in watermelon tourmaline it happens in exactly the pink-to-green sequence that gives the variety its name.
Gem-quality watermelon tourmaline is relatively rare and comes from only a handful of localities worldwide, including Brazil, Madagascar, the state of Maine in the US, and the pegmatite fields of Afghanistan and Pakistan. Our own watermelon tourmaline specimens are sourced from Afghanistan, where tourmaline-bearing pegmatites have produced some of the finest bi-colour and tri-colour material found anywhere.
Like all tourmaline, watermelon tourmaline sits at 7 to 7.5 on the Mohs hardness scale, hard enough for everyday jewellery wear, though as with any coloured gemstone it's worth protecting from hard knocks. Collectors prize natural crystal specimens for the colour banding itself, while cut stones (usually sliced across the crystal to show the full pink-green cross-section) are popular in pendants.
If you'd like to see the colour banding in person, browse our Watermelon Tourmaline collection, every piece is a genuine natural crystal, not a treated or assembled stone.