All tourmalines are striated crystals. They are found in many colours and have very different properties and uses according to their colour. The very best quality coloured tourmalines are hard to find in the healing crystal market (at least at good prices!) as most of the top material is snapped up by the jewellery trade for cutting as gemstones. Tourmalines can also be multi-coloured - bi-coloured ones having 2 colours present within / adjacent to each other; watermelon having a pink central core within a green outer layer. The latter ones make one of the very best crystals for working with the heart and high heart centres. The bi-colour stones are useful crystals for bridging between the energy centres relevant to the colours - e.g: blue / green = throat and heart; red / orange = base and sacral etc. Tourmaline is often found is association with quartz and is a common inclusion, when the quartz acts to strongly amplify and broadcast the tourmaline's energies.