GCAL Unveils New Cut Grade Standards
NEW YORK - After recently introducing a new “Ideal Cut” diamond grading certificate,
Gem Certification & Assurance Lab, Inc. (GCAL) announced the debut of a new cut
grading system. Although the system factors in the traditional gemological criteria of
proportions and finish, it is based primarily on direct assessment light performance, the
first time a cut grade has referenced a directly measured element of the quality of the
"In the past decade, cut has become one of the most important of the famous 4 Cs for
diamonds—so important it is now a recognized factor in diamond grading," explains
Donald A. Palmieri, GCAL’s founder and president. "Until now, however, cut grades have
been based on theoretical computation and computer simulation--not measurement of
actual light performance."
The GCAL cut grade is based primarily on direct-assessment light performance. Using a
comprehensive and thorough 100-point rating system, GCAL scores a diamond for
proportions, finish, and light performance, then integrates all three scores into a final
tally and cut grade. "Those superbly crafted diamonds which earn top point scores for
proportions, finish and light performance are awarded the highest designations of 'Ideal'
or 'Excellent,'" says Palmieri. "These are the most beautiful diamonds money can buy."
Specifically, the GCAL cut grade system relates these three important elements of cut:
Proportions: A round diamond is measured for ten critical cutting factors.
The first six of these--table percentage, depth percentage, crown angle, pavilion angle,
girdle thickness and culet size--comprise the preliminary category in the GCAL cut grade
associated with proportions. Based on a point system, the stone is given one of five
quality grades: excellent, very good, good, fair, and poor. The maximum number of
points for proportions is 30.
Finish: The same five quality grades are used to rate for polish and
external symmetry. The maximum number of points for finish is 30; a maximum of 15 points
each for polish and for external symmetry.
Light Performance: A stone is measured for light performance that consists
of two readings using GCAL proprietary technology—the first for optical brilliance (a contrast
measurement of the diamond's light return versus its light loss) and the second for
optical symmetry (the degree of perfection of its light reflection pattern). The maximum
number of points for light performance is 40; a maximum of 20 points for each of the two
elements of light assessment.
Following the assignment of points, all three critical factors--proportions, finish and light
performance—are analyzed, a final score is given using GCAL’s five-grade quality
ratings system from excellent to poor. If a diamond achieves scores of 30 points for
proportions, 30 points for finish and 40 points for light performance, it earns a final
grade of "Ideal." "If any one of the three scores is less than perfect, the diamond cannot
achieve a grade of 'Ideal,'" says Palmieri. "But given the rigorousness of our grading
system, you can rest assured that a grade of 'excellent' means a diamond is
The new GCAL cut grades are available in all GCAL formats at no additional charge. "Consumers
deserve to know everything about a diamond that contributes to its beauty and value," says
Palmieri. "And since a diamond’s beauty depends significantly on craftsmanship, I can’t think
of any more important information than that which pertains to cutting and performance."
About Gem Certification and Assurance Lab
Gem Certification & Assurance Lab (GCAL) is a subsidiary of Collectors Universe, Inc. In
addition to being the 2007 Official Diamond Grading Laboratory of the JA NY Winter Show, GCAL
is also the Official Diamond Grading Laboratory of the 2007 Fine Jewelry CEO Summit and the
2007 JCK Las Vegas and JCK Invitational Shows, as well as the Platinum Sponsor of the ICA
(International Colored Gemstone Association) 2007 World Congress in Dubai. On the Internet:
CONTACTS: Vanessa Lee
Luxury Brand Group
Donald A Palmieri, President