The objective of grading polished diamonds in order to issue a certificate is first of all a quality determination. Further, in connection with this investigation, the identity of the examined stone is determined. In the first place, each certificate has to confirm that the examined stone is a natural diamond. The identification of an examined diamond is possible, at any time, by way of the at least 16 most important parameters, such as shape, measurements, the so-called identity criteria and especially the quality criteria. The DPL is engaged in grading polished diamonds on the basis of the regulations of the International Diamond Council (IDC), a committee of experts as appointed by the WFDB and the IDMA. The IDC-rules were developed, scientific supported, from the practice.

Measuring - procedures done by newest technology devices and calibrated reference stones guarantee the precision and the ability for reproduction of the certification. Experts with experiences of many years are grading independent of each other, objective and absolutely neutral. The DPL is independent, not involved in the value determination nor the diamond trade.

As an additional service, the DPL offers services for re-polishing diamonds with renowned diamond manufacturers to improve the quality.