It is rightfully considered to be the king of gemstones: Diamond is the hardest natural material in the world. Rough diamonds are polished for use in the watch and jewellery industry and assessed by means of the four "C" criteria: Cut: The cut refers to the individual shape of the diamond. The more meticulously and professionally the stone has been faceted, the more intensively it reflects the light. Certina uses brilliant-cut diamonds for the case and octagon-cut ones for the dial. Colour: At first glance, you would be forgiven for thinking that all diamonds are white. However, experts distinguish between fine nuances in shades - Certina only uses Top Wesselton diamonds. Clarity: Almost every diamond has minimal inclusions which can be detected by a professional through a magnifying glass but are usually invisible to the naked eye. Certina processes diamonds from the coveted VSI (very small inclusions) grade. Carat: The carat is the unit that defines the weight of a diamond. One carat is equal to 0.2 g. The diamonds used by Certina have different carat numbers depending on the model - they are noted for each watch in the sales manual. Certina only uses diamonds which fulfil the conditions of the Kimberley Process, an international system for certifying rough diamonds. It helps to prevent trade in smuggled diamonds - referred to as "blood diamonds" - which are used to finance wars.