What a grading report is for
A grading report is an independent description of one diamond. A lab that does not sell the stone examines it, measures it and writes down what it found. The report travels with the diamond, so you and anyone you later show it to can see what you bought.
It is not a price tag and it is not a valuation. It tells you what the stone is. Price is a separate conversation. But without a report, you are relying only on the word of the seller, and that is not how diamonds should be bought.
Every center stone we show at our showroom on West 47th Street comes with a report, most often from IGI or GIA. Both are well known labs and both grade lab grown diamonds.
IGI and GIA in plain words
IGI
The International Gemological Institute grades a very large share of the lab grown diamonds sold today. If you shop for loose lab diamonds, most of the stones you see will carry an IGI report. Its reports list the familiar grades for color and clarity, plus cut for round stones, and polish and symmetry. Many IGI lab grown reports also note the growth method, CVD or HPHT, and any treatment after growth.
GIA
The Gemological Institute of America created the grading language most of the trade uses, including the D to Z color scale and the clarity scale from Flawless to Included. GIA also grades laboratory grown diamonds. Its lab grown reports describe the stone and clearly identify it as laboratory grown. The format and level of detail have changed over the years, so look at the report itself rather than relying on what you read online.
How to read a report, line by line
Reports differ in layout, but the core information is similar. Here is what to look for, in roughly the order it appears.
| Line | What it tells you |
|---|---|
| Report number | The unique ID. Use it to check the report online and to match the laser inscription. |
| Origin statement | States the diamond is laboratory grown. Some reports add the method, CVD or HPHT. |
| Shape and cutting style | For example, round brilliant, oval modified brilliant, emerald step cut. |
| Measurements | Length, width and depth in millimeters. Useful for working out ratio and face up size. |
| Carat weight | Weight to two decimal places. One carat is 0.20 grams. |
| Color | Graded on the D to Z scale. D is colorless. |
| Clarity | From Flawless to Included, based on what shows at 10x. |
| Cut, polish, symmetry | How well the stone is shaped and finished. Cut grades are usually given for rounds. |
| Fluorescence | Whether the stone glows under ultraviolet light, and how strongly. |
| Inscription | The text laser inscribed on the girdle, usually the report number. |
Some reports also include a plotted diagram of inclusions and a proportions diagram. The plot is a map. It helps you find what the grader saw, and it helps confirm that the stone in your hand is the one on the paper.
Where IGI and GIA differ
For a buyer, the practical differences come down to a few points.
- Availability. You will find far more lab grown stones with IGI reports. That gives you more choice in each shape and size.
- Format. The two labs present information differently and include different extras. Read each report on its own terms.
- Consistency. People in the trade often say one lab is stricter than another on color or clarity. Opinions vary, and grading of any single stone can be debated. The fair approach is to treat the report as a strong guide and let your own eyes make the final call.
This is the reason we put stones side by side. Two diamonds with the same grades from different labs, or even from the same lab, can look different. If one looks better to you, that matters more than the logo at the top of the page. Our guide on choosing a lab diamond in person explains how to compare.
Laser inscriptions
Most graded lab diamonds have tiny text laser inscribed on the girdle, the narrow edge around the widest part of the stone. It usually includes the report number and often a note that the stone is lab grown. You cannot see it with your eye alone. Under a loupe or a microscope it is easy to read.
The inscription does not hurt the diamond and does not show once the stone is set. It links the physical stone to its paperwork. At your viewing, ask us to show it to you. It is one of the simplest checks you can make, and it takes less than a minute.
How to verify a report
- Find the report number on the paper or digital report.
- Go to the grading lab's own website and use its report check tool.
- Compare the weight, measurements, color and clarity with what you were given.
- Match the number to the laser inscription on the stone.
If the online record and the paper agree, and the inscription matches, you can be confident the report belongs to your diamond. Keep a copy of the report with your insurance papers.
What a report does not tell you
A report is precise, but it leaves things out. It does not tell you how bright the stone looks on a cloudy afternoon. It does not tell you whether an inclusion sits in the middle of the table or hides near the edge under a prong. It does not tell you how big the stone will look on your hand.
It also does not tell you the price or the resale value. Lab grown diamonds have low resale value, and a report does not change that. Buy a stone because you love how it looks, not as an investment. Our page on whether lab grown diamonds are real covers value honestly.
Seeing reported stones in person
If you already know the grades you want, use our loose diamond request and pick IGI, GIA or either. We pull three to five matching stones, each with its report, and have them ready on a tray. You can read the reports, check the inscriptions and compare the stones side by side.
To come in, book a viewing at 30 West 47th St, Suite 805, or call (732) 581-7932. You can also browse the shapes first in our shapes guide.
