Imagine that you have bought a diamond whose color, clarity and cut have been graded by the jeweler who sold it to you. Later, you have the stone appraised only to find out that the appraiser has graded the color or clarity lower than what you were told at the store. It turns out that you’ve paid more than the diamond is worth. What has happened? Well, you’ve most likely been sold a diamond whose grade has been “bumped.”
What Is Grade Bumping?
Grade bumping is widely known as the practice of “inflating” the grade of one or more of a diamond’s quality characteristics (i.e. color, cut, clarity, etc.).

Diamond quality grading depends on the opinion of the appraiser.
It should be noted that jewelers are legally not allowed to misrepresent the quality of their jewelry.
However, although there are general guidelines as to how to assess diamond color or clarity, the exact grade comes down to the opinion of the person appraising it.
Since diamond grading is not an exact science, jewelers do have some leeway when grading their own stones.
A jeweler is allowed to represent a diamond’s quality attribute as being within one grade of its original assessment done by an independent professional appraiser.
So, you should not be surprised that some salespeople will present their merchandise in the best possible light, claiming a higher grade than what a more conservative independent evaluator would certify.
Why It Is Important to Buy Certified Diamonds
If a diamond doesn’t have a certificate, you will be relying on the jeweler’s claim about its quality grade.
Keep in mind, however, that if the stone is evaluated by an independent appraiser, its grade may end up being a grade lower.
Therefore, if you buy the diamond based on the seller’s own grading, you may end up paying more than if the stone were certified by the G.I.A. (the Gemological Institute of America).
In order to make sure you are not overpaying for your stone, always buy stones certified by an established authority.
Otherwise, you will be paying for quality that has not been verified by an independent appraiser, and the seller’s personal assessment may always be biased, even if it is not legally a misrepresentation.
What to Pay Attention to When Buying Diamonds
As already mentioned, be wary of stones without a certificate.
If you really want to buy a stone, and it is not certified, insist that it be appraised by an expert before you buy it. This way you will know whether the price asked is reasonable.
Even if the diamond is certified, you should be suspicious of reports issued by unrecognized labs. Some of these appraisers may be connected to the seller in some way and not be impartial.
Do not agree to have the diamond evaluated by an appraiser chosen by the salesperson. It is possible that the lab may not be independent.
Always go for certificates issued by reputable third-party appraisers, such as the G.I.A.
Where to Buy Diamond Jewelry?
We recommend James Allen (read review) because you can see a 360-degree video for any diamond before buying it.
Blue Nile is another reputable diamond retailer we recommend.