T73 Round Brilliant Diamond: the T57's light, with more scintillation and a girdle a setter can seat
Brilliance 93 · Fire 78 · Scintillation 80 · in our census, where the T57 scores 92 · 79 · 72 in diamond
The round every other diamond page on this site is measured against. Here it faces the T57 it grew from, and gains sparkle without losing anything we count.
Rendered in our 3D Gemstone Simulator from the T73 Round Brilliant model, 1.00 ct, studio light.
T73 Round Brilliant Diamond
The T73 keeps the T57's proportions and finishes the girdle with a band of sixteen facets: 57 facets plus sixteen makes 73. This is how most round brilliants are finished today, and it is the benchmark round on our diamond pages.
Because the T73 cannot be set against itself, this page compares it with the T57 Round Brilliant, the knife-edge plan it adds girdle facets to. The two share a 40.75° pavilion. The girdle band makes our model deeper, 61.7% against 59.2%, and it changes one score clearly.
Read the rest of our diamond pages with this one in mind: every pro and con there is a gap to the T73's own figures, Brilliance 93, Fire 78 and Scintillation 80, with 2% of the light leaking.
Is the T73 the best round for diamond? Pros and cons
None by our margins: the T57 is level on every other score.
Compared with the T57 Round Brilliant in diamond.
A difference counts from 3 points (Brilliance, Fire, Tilt, Leakage), 5 (Scintillation,
Symmetry), 2 (Spread) or 5% (weight); Tilt counts as a pro only for a stone within
5 points of the brilliance it is compared with. How we measure.
All eight scores against the T57
At a glance: the T73 Round Brilliant in diamond (white) against the T57 Round Brilliant in diamond (dashed): solid white where
it reaches further, hatched where it falls short. Each pro and con is explained, with pictures, below.
Against the T57 Round Brilliant in diamond: ahead on 5, level on 1, behind on 2.
Global90, the comparison 89, difference +1
Brilliance93, the comparison 92, difference +1
Fire78, the comparison 79, difference −1
Scintillation80, the comparison 72, difference +8
Spread100, the comparison 101, difference −1
Symmetry100, the comparison 100, difference 0
Shape-norm100, the comparison 99, difference +1
Tilt92, the comparison 90, difference +2
Face-up light census, a different measure from the Cut Grading Tool; Spread and Shape-norm above 100 sit on the ring.
Scintillation 80 against 72 for the T57 Round Brilliant in diamond: 8 points higher
Sixteen girdle facets give the stone more surfaces to flash from as it moves, and our scintillation score counts them: 73 facets against 57. The light behind those flashes is unchanged, which is the point of the comparison.
Scintillation follows the number of facets: more facets, more and smaller flashes as the stone moves. Count the facets in each crown. Drawn from each cut's own model.
The T57 does not beat the T73 anywhere by our thresholds. Brilliance is 93 against 92, Fire 78 against 79, Tilt 92 against 90, and both leak 2%. Spread is level too, 100 against 101, even though the girdle band adds depth. The band costs nothing we measure.
Who a T73 diamond suits
Choose the T73 when you want the classic round with a girdle a setter can seat and a polisher would recognise: the published proportions, the T57's light, and more scintillation. It is the round we use as the yardstick for every other cut in diamond.
