The laboratory that guarantees its own grades, which is a materially different promise.
Founded 2001New York3 weighted checks
The Gem Certification and Assurance Lab is unusual in that it backs its reports with a written guarantee: if an independent grader finds the stone differs from GCAL's assessment, the laboratory stands behind it. No other major laboratory makes that commitment, and it changes what the document is.
GCAL certificates include optical performance measurements and photographic evidence — a photomicrograph of the stone and light-performance imaging — which makes matching the report to the stone easier than with a purely textual document.
Verification is online and free, and GCAL inscribes its certificate numbers on graded stones.
GCAL certificates carry a number verifiable on the laboratory's own service, returning the grades issued. The certificate also includes photographic evidence of the stone, which is a stronger matching tool than measurements alone.
GCAL inscribes its certificate number on the girdle of graded stones. Match the inscription to the certificate as with any laboratory.
The written guarantee is part of the product. It is worth reading what it covers, because a guarantee that a stone matches its stated grades is a meaningfully different assurance from a laboratory opinion.
Ordered by how much each one settles. The decisive checks are the ones worth your first five minutes; the supporting ones only matter once those are clean.
GCAL certificates include a photomicrograph of the stone. Compare the inclusion pattern in the photograph against the stone under magnification: inclusions are effectively a fingerprint, and matching them ties the certificate to the diamond more firmly than measurements can.
Have a jeweller read the girdle. The number should match the certificate.
GCAL reports include optical performance measurement. Its absence on a document presented as a full GCAL certificate is worth questioning.
Lovenhall DiamondThe checks tell you how it was made. The instrument tells you what it appears to be, and roughly what its kind fetches.