IGI And NGTC Explained: Lab Diamonds And China National Check

On a lab-grown diamond, the word "lab-grown" on the paper is the point. Here is how IGI and NGTC work.

1. Three Certificates

2. Why Lab Diamond Uses IGI

Lab-grown must be labeled laboratory-grown. IGI was an early grader of lab diamonds and is widely accepted. The paper must clearly state "Lab Grown", or you may be overpaying for a simulant.

3. Reading NGTC

NGTC states whether the stone is natural or lab-grown, treatments (oiling, irradiation), weight and dimensions. For domestic buying, ask for an NGTC re-check.

4. Avoiding Fake Papers

1. Match the girdle number.
2. Beware vague labels.
3. Re-check expensive stones yourself.

Natural paper: GIA guide. The 4Cs: 4Cs.

4. IGI vs GIA For Lab Diamonds

GIA is stricter and grades lab diamonds conservatively. IGI is the dominant lab for lab-grown stones and grades them more warmly. Some buyers find IGI grades slightly generous, but for lab diamonds the price is already low, so the practical difference is small. The key point is that the report explicitly says laboratory-grown.

5. Reading NGTC

NGTC is China's national lab. Its report states whether the stone is natural or lab-grown, treatments, weight and dimensions. For domestic online purchases, ask for an NGTC re-check; it is the most authoritative domestic paper and is accepted in disputes.

6. Avoiding Fake Papers

Match the girdle number, verify online, and re-check expensive stones. Vague wording like "diamond" without "natural" or "lab-grown" is a warning sign.

7. Why Lab Diamonds Need A Report

Without a report, a cheap simulant can be sold as a lab diamond. The report proves it is real diamond and discloses the growth method. For any lab stone over 3,000 yuan, the report is non-negotiable.

8. Domestic Re-Check

Buying online? Ask the seller to ship to an NGTC office for re-check before delivery. The small fee protects you from swapped stones and fake papers.

8. Why Vague Wording Fails

A paper that says only "diamond" without natural or lab-grown is a red flag. Reputable labs always state the origin explicitly. Walk away from vague wording.

9. Domestic Re-Check

For online purchases, route the parcel through an NGTC office. The small fee confirms the stone and protects you from swapped goods.

10. Reading The IGI Report

IGI reports for lab diamonds list growth method, shape, measurements and clarity. The measurements let you verify the stone's proportions. Always confirm the girdle inscription matches.

11. When NGTC Helps

NGTC is trusted domestically for re-checking imported stones. If a private seller refuses an NGTC re-check, that refusal tells you everything.

12. Digital Verification

Both labs offer online report lookup. Enter the report number before paying. A mismatch means fake paper.

13. Why Vague Papers Fail

A report that says only "diamond" without "natural" or "lab-grown" hides the origin. Reputable labs state growth method explicitly. If the paper is vague, assume the worst.

14. The Re-Check Routine

For online purchases over a few thousand yuan, route the parcel through NGTC before delivery. The small fee confirms the stone and the paper match. This single step prevents most online jewelry fraud.

15. Digital Report Lookup

Both IGI and NGTC let you verify report numbers online. Enter the number yourself, not through a link the seller sends.

16. Why Lab Diamonds Need Papers

Without a report, a cheap simulant can be passed as a lab diamond. The report proves it is real and discloses growth method. For any lab stone over a few thousand yuan, the report is non-negotiable.

17. Re-Check Before Delivery

Route expensive online orders through NGTC. The small fee confirms the stone matches the paper. Sellers who refuse have something to hide.

18. Online Verification

Look up report numbers yourself; do not trust links the seller sends.

19. Vague Wording Fails

"Diamond" without natural or lab-grown hides origin. Reputable labs always state growth method. Vague wording is a warning sign.

20. Re-Check Online Buys

Route expensive online orders through NGTC before delivery. Sellers who refuse have something to hide.

21. Verify Independently

Look up report numbers yourself, not through seller links.

22. Why Papers Matter For Lab Diamonds

Without a report, a cheap simulant can be sold as a lab diamond. The IGI report proves it is real diamond and discloses the growth method. For any lab stone over a few thousand yuan, the report is non-negotiable.

23. Re-Check On Arrival

Route expensive online orders through NGTC. Sellers who refuse a re-check are hiding something.

24. Verify Numbers Yourself

Look up the report on the lab's official site. Do not trust links the seller sends.

25. Vague Wording Fails

"Diamond" without origin stated is a warning sign. Reputable labs always disclose growth method.

26. Re-Check Online Buys

Route expensive orders through NGTC before delivery.

27. Verify Numbers Yourself

Look up report numbers on the official site.

28. Final Checklist

Verify the report online, re-check expensive online orders, and reject vague wording. A real stone comes with a clear paper; sellers who refuse verification have something to hide.

29. Final Thought

The report is part of the stone. Verify it online, re-check expensive online buys, and reject vague wording. A real diamond comes with a clear paper; sellers who refuse have something to hide.

30. Why Lab Diamonds Need A Report

Without a report, a cheap simulant can be sold as a lab diamond. The report proves it is real diamond and discloses the growth method. For any lab stone over a few thousand yuan, the report is non-negotiable.

Verify online, re-check expensive orders, and reject vague wording. The paper protects the stone.

If a seller refuses to let you route an expensive order through an independent lab, treat that refusal as the answer, because honest vendors have nothing to hide from verification.