The short answer: A certified LEO diamond has been graded by an independent laboratory, GSI (Gemological Science International). Every LEO center stone comes with a GSI report on the 4Cs and all center stones are also rated “Excellent” for brilliance, fire and scintillation, the three measures of how a diamond handles light.
Key takeaways
- Certification is written proof, from an independent lab, of a diamond’s quality.
- LEO center stones are certified by GSI, one of the leading gemological laboratories in the world.
- A GSI report covers the 4Cs: cut, carat weight, color and clarity.
- GSI also rates light performance. Every center stone is rated “Excellent.”
- You can look up any LEO certificate online.
What is diamond certification?
Many diamonds look alike at first glance, but they aren’t all equal in quality. A diamond certificate, also called a grading report, is a document from an independent gemological lab that records a specific diamond’s characteristics. It gives you an objective way to compare quality and price, whether you’re looking at two rings in the same store or shopping across retailers.
Certification is sometimes called the “5th C” because it confirms the other four. Read more in Certification: The 5th C.
Who certifies LEO diamonds?
LEO center stones are certified by Gemological Science International (GSI), an independent gemological laboratory based in New York’s Diamond District, with offices in diamond centers around the world.
Independence is the point. Leo Schachter cuts the diamonds, and a separate lab grades them. That separation is what makes the report something you can rely on.
What a LEO GSI report includes
| Report Field | What It Tells You |
|---|---|
| Report number | The unique ID you use to look up and verify the report |
| Shape and cut | The diamond's shape and cutting style, for example LEO® Round |
| Measurements | The diamond's dimensions in millimeters |
| Carat weight | How much the diamond weighs |
| Color | How close to colorless the diamond is |
| Clarity | How many and how visible the natural inclusions are |
| Polish and Symmetry | How smooth the facets are and how precisely they line up |
| Laser Inscription | The ID number inscribed on the diamond's girdle, which matches the report |
| Light Performance | Ratings for brilliance, fire and scintillation |
What “Excellent” brilliance, fire and scintillation mean
Light performance describes what you actually see when you look at a diamond. It’s measured in three parts:
| Measure | What It Is | What You Notice |
|---|---|---|
| Brilliance | The white light a diamond reflects back to you | How bright the diamond looks |
| Fire | Light split into flashes of rainbow color | Colorful sparks as you move |
| Scintillation | The pattern of light and dark across the diamond as it moves | The "sparkle" or twinkle effect |
Every LEO center stone is rated “Excellent” by GSI on all three.
Where “brighter” comes from
THE LEO Diamond was the first diamond independently certified to be visibly brighter. That’s possible because of its patented cut: 66 facets instead of the 57 or 58 on a conventional round brilliant, with the additional facets placed to increase light return. See how the two compare in LEO Cut vs. Round Brilliant.
Today, every LEO center stone is certified by GSI, and light performance ratings give you a measurable way to judge brightness instead of relying on how a diamond looks under one store’s lighting.
How to verify your LEO certificate
- Find your report number. It’s on the GSI report that came with your diamond.
- Check the laser inscription. Your jeweler can show you the ID number inscribed on the diamond’s girdle with a loupe. It should match the report.
- Look it up online. Enter the number in Find Your LEO Certification.
- Lost your paperwork? Bring the diamond to an authorized LEO jeweler, who can read the inscription and help you locate the report.
Questions to ask before you buy
- Which lab graded this diamond, and can I see the full report?
- Does the report number match the laser inscription?
- Does the report include light performance ratings?
- How does this diamond’s light performance compare to others at a similar price?
Already own a LEO?
Look up your diamond’s GSI report in seconds.
Still shopping? Find a jeweler near you or shop THE LEO Legacy at Kay.com.
Frequently asked questions
Who certifies LEO diamonds?
LEO center stones are certified by GSI (Gemological Science International), an independent gemological laboratory headquartered in New York. Leo Schachter does not grade its own diamonds.
Does every LEO diamond come with a certificate?
The center diamonds in LEO solitaires and engagement and bridal rings are GSI certified. Smaller accent diamonds in a setting are typically not graded individually.
What does “Excellent” light performance mean?
It means GSI gave the diamond its top rating for brilliance (white light), fire (colored light) and scintillation (sparkle). Every LEO center stone receives an “Excellent” rating on all three.
How is GSI different from GIA?
Both are independent gemological labs that grade diamonds on the 4Cs. What matters most for a shopper is that the grading is independent and that the report number matches the inscription on the diamond.
How do I find my LEO certificate online?
Enter your report or inscription number in the Find Your LEO Certification tool on theleo.com.
