What Is GCAL 8X Certification?

What are the eight criteria in GCAL 8X?

GCAL grades each factor on a five-step scale: Poor, Fair, Good, Very Good, Excellent. To earn 8X, a diamond needs Excellent in all eight. The certificate groups them into three categories.

On a round, factor 8 is Hearts & Arrows: eight arrows through the crown and eight hearts through the pavilion, photographed on the report. Our guide to hearts & arrows and super ideal cut covers it in depth.

On a fancy shape, GCAL scores shape aesthetics instead: outline, axis symmetry, length-to-width, and, on ovals and cushions, how little bow-tie shows. GCAL publishes 8X for oval, princess, pear, marquise, radiant and cushion. Read the certificate for that stone, and see lab-grown diamond shapes for what to check in each.

Only three of the eight factors are light performance. 8X is mostly how precisely the diamond was made. That precision is what lets it perform.

How do you read a GCAL 8X certificate?

The certificate packs a lot onto one page. Here is what each part tells you.

Identity and the 4Cs

Certificate number, "Lab Grown Diamond," shape, measurements in millimeters, carat, color, clarity, fluorescence, girdle and culet. The measurements are how you confirm the stone in hand is the stone on paper, and they are what a jeweler uses to size prongs. For how these grades apply to lab-grown stones, see the 4Cs for lab-grown diamonds.

Growth method

GCAL states how the diamond was grown, HPHT or CVD, along with the diamond type.

Performance images

This is the part a standard report doesn't have. You will see an optical brilliance map, a scintillation image built from nine positions, an optical symmetry image, and actual photographs of the crown and pavilion, which for a round are the hearts and arrows patterns. Fire is shown in a video online.

On the brilliance map, white means light returned to your eye and dark blue means light lost. On the symmetry image, you are looking for an even, regular pattern. Irregular or lopsided shapes point to facets that are slightly off.

Fancy shapes get the same images. Here is what they look like for an 8X cushion, including the scintillation image, where each white flash is a point of sparkle.

Proportion diagram

A scanned diagram shows table, depth, crown angle and height, pavilion angle and height, girdle, culet, and star and lower-girdle lengths. The sample certificate above reads table 57%, depth 61.5%, crown 34.5°, pavilion 40.8°.

Clarity plot and identification

The clarity plot maps the stone's characteristics, such as needles or a cloud. A Gemprint optical fingerprint and a QR code link the stone to its online record.

What does GCAL's consumer guarantee cover?

GCAL backs its grading with a written guarantee. It is useful, but it is narrower than the name suggests.

• What it covers: the accuracy of the carat weight and the cut, color and clarity grades on the certificate, plus the natural or lab-grown identification. It applies to lab-grown stones.
• Conditions: the claim must be made within two years of the certificate date, the diamond must be unmounted, and you need the original retail receipt and the original certificate. Damaged, treated, re-polished or re-cut stones are excluded, and a challenge fee and return shipping apply.
• Payout: the difference between what you paid and the current fair-market value of an equivalent diamond, as determined by GCAL.

It is not insurance against loss, theft or damage. Keep your receipt and certificate somewhere safe. Claims require the stone unmounted, so if you question a grade, raise it before the stone is set.