When making a substantial purchase, such as a diamond, it is important to make sure it is certified. You should not take a risk on a diamond that is sold without an official certificate. The only exceptions to this rule relate to rings where the central diamond is very small, i.e. anything that is less than 0.30 carats. 

The most well known certificate is the one that is supplied by the Gemological Institute of America (GIA), however, there are various types of diamond certification available. No matter what grading lab has conducted the assessment of the diamond, if you choose an official body, you can be sure that it has been conducted by a specialist who is unbiased and experienced. They will authenticate the diamond's attributes, evaluating the colour, weight, and clarity of the diamond. If you are buying a Round Brilliant diamond, you can expect the cut to be graded as well. 

Another point worth bearing in mind is that laser inscriptions are now used to mark diamonds that have been certified. This is to protect the customer. You can have the peace of mind that the diamond you are buying has been certified by an authentic grading body. In most cases, the inscription will be located on the diamond's girdle. It is easy to find using a magnification loop. 

Moreover, there are some laboratories that are stricter than others, and the GIA is widely known as being one of the strictest. It ranks clarity and colour higher than other labs, although HRD and AGS are not far off their standards. In regards to HRD, they have an extra grading for clarity, which is known as Loupe Clean. This is a term utilized for all diamonds that have impurities that are invisible.