A diamond certificate also called diamond grading report, diamond dossier or diamond quality document verifies that a diamond is genuine and evaluates the quality and size of the stone. A diamond certificate is a document issued by a Gemological Laboratory, detailing the ‘grade’ which indicates the physical properties of the diamond.
The ‘physical properties’ as they call it being the cut, clarity, colour, symmetry and carat of the stone and other characteristics. Many round diamonds will also include grade on the report. A certificate is a document, which retains its value over a long period of time, assuming the diamond is not chipped or otherwise altered.
You have to be careful though not to confuse certification with an appraisal. And this tends to happen often! An appraisal is an indication of the financial value of the piece under consideration. The financial value of a diamond can easily change over time and appraisals are most commonly used for insurance purposes.
A certificate enables you to buy your diamond with confidence. A diamond certificate, however is only useful if it has been issued by a reputable independent laboratory.
There are several reputable gemological laboratories throughout the world. Laboratories like Anchor Cert – part of the Birmingham Assay Office, IGI (International Gemological Institute) based in Antwerp, EGL (European Gemological Laboratory USA), GLG (Great Lakes Gemological Laboratory) based in Mumbai, ‘HRD’ (Hoge Raad Voor Diamont) based in Antwerp, Belgium and the GIA (Gemological Institute of America) based in the USA are some of the well known worldwide laboratories.
Each product that is certified is indicated by a blue or black sign in the corner of the product picture.

Only a decade or two ago, many British or European retail jewellers offering diamond jewellery could not really tell you the weight of the diamonds in a diamond ring they were selling you, and some still can't today!
Things have improved over the years, but many retail jewellers still cannot tell you accurately the quality of the diamonds you are expected to buy from them. Recently, many jewellers, particularly the large multiple retailers, have realised that they need to appear to their customers as being more expert, and many have introduced graded diamonds into their ranges, or offer grading info about diamonds from their stock.
You should expect a laboratory certificate mainly if you are spending over £1,000 on a diamond or buying it from an unknown source. On the other hand, you should always ask for a certificate as it is a sign of a high quality diamond.