An attractive man made stone with fibrous properties, available in a myriad of different colours. Chatoyancy is an optical reflectance effect seen in certain gemstones. Coined from the French œil de chat meaning cat's eye chatoyancy arises either from the fibrous structure of a material as in tiger eye quartz or from fibrous inclusions or cavities within the stone as in cat's eye chrysoberyl. The luminous streak of reflected light is always perpendicular to the direction of the fibres. For a gemstone to show this effect best it must be cut en cabochon with the fibres or fibrous structures parallel to the base of the finished stone. Faceted stones are less likely to show the effect well.