Diamonds certified by the Gemological Institute of America (GIA) have an associated report that gives you important information about the diamonds. Jewelers and diamond sellers who want to be sure their gemstones are authentic try to have them graded and certified. This is more than just someone looking at the diamond and saying it's real. These reports and the certification verify the grade of the diamond along with a lot of other information.
Is That Diamond Actually Fancy-Grade?
One very helpful feature for people who aren't familiar with diamonds is the ability of the report to distinguish between "white" diamonds that fall on a spectrum and diamonds that truly have a color to them. White diamonds are the typical clear diamonds that you think of, and they can actually come in a range of shades that trend toward light yellowish and light brownish. These are never actually a bright yellow or dark brown, though, and they're given a letter grade. Fancy-color diamonds, though, have an actual hue; a fancy yellow diamond will be unmistakably bright yellow, for example. The certification and report can tell you whether the light yellow stone you see is actually fancy-color or merely a lower color grade of white diamond.
Is That Diamond Mined or Lab-Grown?
It is very hard nowadays to tell the difference between diamonds that are from mines and those that are from a lab. They are chemically the same. Lab-grown diamonds that are known to be lab-grown should have an identification number imprinted on the girdle, the thin band that is faceted into the stone. But if you're not sure if the diamond is mined or lab-grown, you can have GIA test it and issue a report. The jeweler selling the diamond should already have done that.
Is the Report Itself Real?
GIA-certified diamonds are supposed to be diamonds you can trust. However, a simple report can be faked, and anyone using that fake report can claim certification. When a diamond is certified, however, there's an ID number. You can ask the jeweler for the report ID number and actually look it up on the GIA website to verify the number. If the report is real and the diamond is real, you know you can be confident buying from that particular diamond seller, and you know that what you're getting is a real diamond that is worth the money you're paying.
Contact a local jeweler to learn more about GIA-certified diamonds.