Source and scope
What GIA found. What I would check.
Source and scope: The findings belong to GIA Gems & Gemology. This is a public laboratory case, not a YDG client purchase. GIA did the testing. I explain what I would ask before buying a stone with this kind of origin claim. The article gives no buyer or seller outcome.
- Finished gem
- 0.64 carat cushion modified brilliant
- Color reported
- Fancy grayish greenish blue
- Publication
- Spring 2019
Laboratory evidence
The natural base and CVD layer needed separate answers.
GIA examined a 0.64 carat Fancy grayish greenish blue cushion modified brilliant. The spectroscopy showed an unusual combination of nitrogen and boron related features. Immersion and other tests showed a natural substrate and a CVD grown layer. GIA described a thick overgrowth, rather than a simple surface coating. The layer contributed gray and blue, while the natural part contributed yellowish color.
You cannot settle this from a normal shopping video. GIA needed the actual stone and laboratory tests. Its images show what the researchers found under those conditions.
GIA traced growth through the added layer.
GIA traced dislocation bundles from near the boundary upward and outward through the CVD layer. That supported a thick overgrowth, rather than a thin coating. This view uses crossed polarizers in immersion and spans 1.90 mm. It does not show the diamond’s everyday face up color.
The microscope view spans 1.90 millimeters and uses crossed polarizers in methylene iodide immersion. GIA observed dislocation bundles beginning at or near the interface and growing upward and outward into the CVD layer. The observation supported a thick overgrowth rather than a thin surface coating. This is the same 0.64 carat stone from the Spring 2019 case. The microscope lighting does not represent normal face up color.
Read the full claim
Whole stone origin and color origin are different questions.
| Claim in a listing | What to request |
|---|---|
| Natural diamond | The full GIA report identifying the whole stone. |
| Fancy color | A clear account of color origin and any treatment or composite structure. |
| Rare or unusual look | The actual stone, full documentation, and a return path long enough for verification. |
For natural diamonds, I start with GIA. A report number and a seller description are useful only when they describe the actual diamond being sold. This case shows why a complicated origin claim needs more than a quick visual opinion.
What the case establishes
Like the color? Ask how it got there.
An unusual color is a reason to ask how it got there. It is not proof that anything is wrong. This one case cannot tell us how common composites are. Get the full report and let the lab answer the origin question.
Read our natural diamond verification guide and natural versus lab guide for the ordinary purchase path.
Your purchase
What I would ask before buying.
Bring the entire description and the complete report when the seller uses an unusual origin claim. A cropped video cannot carry that explanation.
- Request the full GIA report for a natural diamond purchase.
- Read the color origin and treatment information.
- Ask for an explanation of any composite or overgrowth finding.
- Plan enough return time for qualified verification.
Buyer questions
Your questions, answered
Was the stone natural or lab grown?
Both. The base was natural diamond. The CVD layer was lab grown. Calling the whole stone natural leaves out the part GIA found on top.
Can I see a CVD layer in a seller's video?
Do not count on it. GIA used laboratory methods. Ordinary video can show beauty, not prove this structure.
Is every blue diamond a composite?
No. Blue alone tells you very little about how the color got there. Ask for the full report and its color origin finding.