Does a GIA Certificate Increase Diamond Value?

Short answer: a GIA report does not make a diamond better, but it usually makes the offer higher — because it removes the uncertainty a buyer would otherwise price in. Whether that is worth the cost and delay of getting one depends on the stone.

What a GIA report is

The Gemological Institute of America is the laboratory whose grading the trade treats as the reference standard. A GIA Diamond Grading Report states the stone’s measurements, carat weight, color and clarity grades, cut grade (for rounds), polish, symmetry, fluorescence, and a plot of inclusions, and it usually corresponds to a microscopic laser inscription on the girdle. It is a description, not an appraisal: it does not state a value.

Why it raises offers

When a buyer evaluates an uncertified diamond, they grade it themselves — but they know their own grading could be a step off, and they know the next buyer down the line will make the same allowance. So they price toward the lower end of the plausible range. A GIA report collapses the range to a point. The buyer can price the exact grades against exact comparables and resell the stone more easily, and more of the value comes through to you.

The effect is largest where a single grade step is worth the most: stones of one carat and up, and stones in the higher color and clarity ranges. For a 2-carat stone, the difference between G and H color, or between VS1 and VS2, can be thousands of dollars, and a report settles it. For a 0.40 ct stone, it is tens of dollars.

When it is worth getting one before selling

Getting a report costs a fee based on weight and takes a few weeks (GIA’s New York laboratory is in Midtown; Carlsbad, California is the other). As a rule of thumb:

• Over about 1 carat: usually worth it, especially if the stone is likely F–I color and VS–SI1 clarity, where grades matter most.
• 0.70–1.00 ct: often worth it for a well-cut stone; ask a buyer to grade it first and tell you.
• Under about 0.70 ct: usually not; the fee eats the benefit.
• Any size, if you suspect the stone is exceptional (D–F color, VVS or better) or is a fancy color: yes, and for fancy colors a report is close to essential.

An honest buyer will grade your stone free of charge and tell you whether a report is likely to pay for itself. We do this at both our offices.

Other laboratories

• AGS (now merged into GIA) reports are respected, particularly for cut.
• IGI is widely used and generally reliable; it is also the main lab for lab-grown diamonds, so check that the report says “natural.”
• EGL (various entities) and most jeweler-issued “certificates” tend to grade one or more steps generously. Buyers treat them as descriptions and regrade the stone. A generous EGL grade does not raise the offer.
• Insurance appraisals state retail replacement value, which is not resale value, and often use inflated grades. Useful for identification only.

An old GIA report

GIA’s standards have been stable for decades, so an old report is still meaningful. A buyer will verify that the stone matches (inscription, measurements, plot) and that it has not been chipped or recut since. GIA also offers a report update for a fee.

Bottom line

A GIA report will not turn an ordinary diamond into a valuable one. It will make sure a good diamond is paid for as a good diamond. If you are unsure about yours, bring it to our Atlanta or New York office; we will grade it, tell you what a report would likely do, and make an offer either way.