Tourmaline Pebble colours ranging through pinks and greens, the polished gemstones approx 9x4mm to 5x4mm dimensions. Tourmaline is a gemstone that can come in all sorts of colours and is, indeed, colour-wise, one of the most variegated of all gemstones, and is one of those gemstones that will present different colours in the same crystal. There is a good example of this, called “Rainbow Tourmaline” in the “Other Gemstone” section of this Christopher William website, five items in from the end of that “Other Gemstone” segment, set in a costly Sydney-handmade 18ct Gold ring.