A diamond’s “certificate” is its grading report. One of the major benefits in buying a diamond with a lab report or quality assessment is to get an expert opinion from a party that has no vested interest in selling you the diamond. Knowing which lab issued that report is important, since diamond grading is not standardized. For example, a diamond reported as F in color at a lab with relaxed standards might receive G, H, or lower at a more reputable lab. Some labs don’t report all measurements. Some give no description or grade for cut. These differing standards and practices can be confusing for consumers. Lax grading standards can give the buyer a false or negative impression about the appearance or value of a diamond that has been graded using stricter standards. Diamonds that have been graded using softer standards are often carried by chain stores, mall and discount outlets, and “wholesalers”. In some cases, the labs being used are wholly or partially owned by the stores that are selling the diamonds. This factor totally voids any benefit of buying a diamond with a report from that lab.
Two diamonds that appear to have very similar lab reports can be vastly different in their values. A report from a reputable, consistent lab is a good place to start. It is also important to find a qualified expert that you feel comfortable with, to interpret the differences between the two reports. Do not rely solely on a piece of paper to make your decision. We will be happy to consult with you and offer you the benefit of our expertise and an honest opinion as to which diamond is the better value, and if there is one that would better suit your needs.
AGS and GIA Grading Reports
These organizations were both founded by Robert Shipley in the 1930s and undisputedly employ the most strict and consistent standards. Diamonds with reports from the AGS or GIA command a higher premium and hold their value better than diamonds from “softer” labs.
The Gemological Institute of America (GIA) has the strongest worldwide reputation for independence and consistency. The world’s largest and most valuable diamonds have been sent there for decades thanks to their constant color and clarity strictness.
The American Gem Society (AGS) is the world’s elite cut grading laboratory. Smaller in scope than the GIA, they enforce the same color and clarity standards while focusing more strictly on cut craftsmanship and scientific light performance.
Cut and Grading Reports
Most common reports have no grade for cut. Others use outdated ranges or unproven systems to assign (typically liberal) grades. The vast majority of grading reports seen in mainstream markets are issued by these labs.
The GIA enjoys a long-standing reputation as the global diamond grading authority.