The Certification score
Certification measures whether the stone's paperwork deserves trust: the reputation of the grading laboratory, the completeness of the published record, and the presence of a verifiable certificate.
Laboratory reputation is scored from a published table reflecting the consistency and strictness each laboratory is known for. GIA anchors the scale at 100. A laboratory we do not recognise scores 60, and the absence of any laboratory scores 30.
Data completeness covers 18 fields from the core grades to physical measurements. Records that publish everything score full marks; sparse records lose points in proportion to the evidential weight of what is missing.
Components and weights
| Component | Weight | Label |
|---|---|---|
| Laboratory reputation | 40 | |
| Data completeness | 40 | Data completeness (40 points) is the weighted share of 18 fields present on the record, using the weights in Table 5.3. |
| Certificate availability | 20 | Certificate availability (20 points): certificate number with a certificate document on record scores 100; number plus named laboratory scores 80; number alone scores 60; laboratory alone scores 40; neither scores 10. |
The integrity gate
A record that claims a certificate and a laboratory but is missing color or clarity contradicts itself: certified stones always have those grades. Such records are capped at 30 regardless of their other components.