A diamond certificate is completed by a third-party. A 3rd party certification is recommended as it would be easy for an unscrupulous jeweller to take advantage of an uninformed buyer and sell him/her a stone, which ostensibly has much better characteristics than it really does. There are a number of ways unsuspecting buyers might land a bad deal. If the diamond is not certified, there is a good chance you may be buying a stone that is one or more grades below stated values in terms of carat weight, colour, clarity, or cut. Without a certificate, issued by a reputable agency, such as GIA, IGI or HRD, a buyer relies on a jeweller’s integrity that the diamond’s 4C parameters are accurate and not overstated.