Is a grading report (or certificate) all I need to protect myself when buying a diamond?

No. While grading reports are fantastic tools, the majority of them don't give you enough information regarding the quality of a diamond to determine if it's priced correctly.

Moreover, many diamonds are fractured filled after they are graded or "certified." Fracture filling, although it enhances the appearance of the diamond initially, is not permanent. Once the filling falls out, the diamond becomes cloudy and unattractive.

In addition, many diamonds also have surface-reaching breaks, not all of which are disclosed on even the most reliable lab's grading reports. These breaks can lead to durability issues, light leakage, and motivate dealers to use fracture filling.