Back to: Diamond Grading Basics
Reputable gemological laboratories, like the GIA Laboratory and EGL, are the most consistent and dependable sources of diamond grades. The grades are recorded on diamond grading reports that list the quality factors represented by the Four Cs: clarity, color, cut, and carat weight.
Diamond grading reports—some people call them certificates, or certs—date back to the middle of the twentieth century. They’ve become an enormously important part of the modern diamond trade.
Gemological laboratories grade hundreds of thousands of diamonds a year. That much repetition makes the grades on the reports highly reliable and consistent.
Systems at most major gemological laboratories are adapted from the GIA Diamond Grading System because other labs know that the GIA system is universally accepted. Even if a grade is based on the GIA system, however, the only source of an authentic GIA diamond grade is the GIA Laboratory.
A quality report from a reputable lab allows a retailer or dealer to choose a diamond without seeing it. Imagine that a South African retailer in Cape Town, needs a center stone for a ring he’s designing. He contacts dealers in Bedfordview Diamond Centre or the diamond hub in Rosebank to see what they have in stock.
A Johannesburg dealer has the diamond he’s looking for: a 5.26-ct. G-VS1 round brilliant with a cut grade of Excellent. The dealer WhatsApp’s the jeweler a copy of the diamond’s grading report. The retailer likes what he sees in the report and orders the diamond sight-unseen. Transactions like this happen every day, with diamonds being constantly bought and sold on the strengths of their reports.
A report can also work the other way: You can check a diamond that’s accompanied by a quality report to make sure it matches its description. This protects you against switched stones.
And now, GIA Report Check is available for all GIA reports, providing you with an additional level of assurance. With Report Check, you can quickly and conveniently confirm that the information on your report matches what is archived in the GIA report database.
GRADING RESULTS
| Shape | Round Brilliant |
| Measurements | 11.16 – 11.20 x 6.87 mm |
| Carat Weight | 5.26 carat |
| Color Grade | G |
| Clarity Grade | VS1 |
| Cut Grade | Excellent |
PROPORTIONS
| Depth | 61.5% |
| Table | 59% |
| Crown Angle | 34.5° |
| Crown Height | 14.0% |
| Pavilion Angle | 41.4° |
| Pavilion Depth | 44.0% |
| Star Length | 55% |
| Lower Half | 80% |
| Girdle | Medium to Slightly Thick, Faceted, 3.5% |
| Culet | None |
FINISH
| Polish | Excellent |
| Symmetry | Excellent |
FLUORESCENCE
| Fluorescence | None |
CLARITY CHARACTERISTICS
| Clarity Characteristics | Crystal, Cloud, Needle |
| Key To SymbolsCrystal Cloud Needle |
COMMENTS
| Additional clouds are not shown. Pinpoints are not shown. |
INSCRIPTION(S)
| GIA 6223640075, [ORIGIN SYMBOL] |
ORIGIN RESULTS
| Country Of Origin | South Africa |
| *Origin is determined via documentary evidence from the miner. Scientific matching of rough to polished performed by GIA. | |
| Diamond as rough and polished. Images are not to scale and do not reflect the actual size of each item. | |
Diamond certificates are often issued by gemological laboratories to assess the quality of a diamond. The GIA certificate is one of the strictest and most internationally recognized certificates.