Generally, all are less hard than diamond. Moissanite basically has an increased refractive index than diamond, and when offered beside an equivalently sized and Lower diamond will show a lot more "fire". In really uncommon instances tourmaline is found in blue color, most famous being Paraiba tourmaline and indicolite tourmaline. https://gemstones-cape-town29639.frewwebs.com/31120327/detailed-notes-on-gemstones-south-africa