Diamond guide
Diamond certification explained
A grading report is an independent laboratory’s assessment of a stone, so a buyer, a retailer and their client all trust the same facts. Every certified diamond Kiran supplies carries a report from GIA, IGI or HRD.
What a report certifies
- The 4Cs: cut grade, color, clarity and carat weight.
- Polish and symmetry, the two finishing grades that sit alongside cut.
- Proportions that drive light performance: table percentage, depth percentage, crown and pavilion angles, girdle thickness and culet.
- Fluorescence, and the stone’s exact measurements in millimetres.
- A unique report number, often laser-inscribed on the girdle, that ties the stone to the certificate.
GIA, IGI and HRD
Three independent gemmological laboratories grade the stones a wholesaler handles day to day. Each publishes its standards and an online report-check tool, so a report number can be confirmed against the lab’s own records.
| Laboratory | Where it leads | Notes for the trade |
|---|---|---|
| GIA | Natural diamonds | The long-established reference; the strictest and most widely recognised at the top of the market. |
| IGI | Natural and laboratory-grown | Broad trade coverage and fast turnaround; consistent grading across large volumes. |
| HRD | Natural diamonds (European origin) | Antwerp-based; recognised across European and international markets. |
Reading a report as a buyer
A seasoned buyer looks past the headline grades to the proportions. Table and depth percentages, crown and pavilion angles and girdle thickness explain why two stones of the same color and clarity can perform, and price, differently. A strong cut grade with clean polish and symmetry signals a stone that will look brighter on the counter and photograph well online.
Fluorescence is worth reading rather than fearing: faint to medium blue is often immaterial and can be bought at a small discount, while strong fluorescence in a high-color stone deserves a face-up check.
Why certification underpins the trade
For a retailer, the report is a sales tool and a guarantee: it backs the quality claim you make to your client and supports insurance and valuation. On memo, the report number is the record that follows the stone out and back, so both sides reconcile against the same facts. For the end client, it is proof of exactly what they own. This is why Kiran trades certified stones and keeps the lab and report number on every line.
See the 4Cs for what the grades mean, responsible sourcing for where the stones come from, or request trade access to search certified stones at your account pricing.
Common questions
Is a GIA report better than IGI or HRD?
All three are independent laboratories that grade to published standards. GIA is the long-established reference for natural diamonds; IGI and HRD are widely used across the trade. What matters is that the stone is graded by a recognised lab and the report number matches the inscription on the girdle.
What is the difference between a grading report and an appraisal?
A grading report states a stone’s measured facts, the 4Cs, proportions and finish, without a price. An appraisal assigns a monetary value for insurance or resale and reflects the market at a point in time. Kiran supplies the grading report; the retailer or an independent valuer issues the appraisal.
Can a diamond report be verified?
Yes. Each lab publishes a report-check tool where the report number returns the full grading. On many stones the number is laser-inscribed on the girdle and readable under magnification, tying the certificate to the specific diamond.
Does every stone Kiran supplies carry a certificate?
Certified stones ship with a GIA, IGI or HRD report and the report number on file. Melee and small accent stones are supplied to grade rather than individually certified, which is standard trade practice.
