---
title: "T73 benchmark: meaning in gemology"
description: "The T73 benchmark is the round brilliant that our tools compare every cut with, in the same gemstone. It has Tolkowsky's 1919 angles and table, and 73…"
url: https://digitalgemology.com/learn/glossary/t73-benchmark
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · How we measure

# T73 benchmark

Also called T73 Round Brilliant, benchmark round

The T73 benchmark is the round brilliant that our tools compare every cut with, in the same gemstone. It has Tolkowsky's 1919 angles and table, and 73 facets: 57 plus 16 girdle facets.

## In more detail

Its main crown angle is 34.5° and its main pavilion angle 40.75°, with a 53% table. In diamond it reads 93 for brilliance, 78 for fire and 80 for scintillation in our census. It is a reference, not a top score: five cuts score higher overall in diamond.

## How we measure it

The Cut Performance Wheel draws the T73 as a dashed outline. Each cut-page bar shows a thin mark for it. The Cut Grading Tool traces its brilliance and light maps on the T73.

## Related terms

- [Cut Performance Wheel](https://digitalgemology.com/learn/glossary/cut-performance-wheel): The Cut Performance Wheel is a free Digital Gemology tool. It draws eight light-performance scores of one cut, in one gemstone, on a wheel.
- [Cut Performance Index](https://digitalgemology.com/learn/glossary/cut-performance-index): The Cut Performance Index is Digital Gemology's open table of light-performance scores for the cuts we sell, in seven gemstones. It gives each cut brilliance, fire, scintillation, tilt, symmetry, spread, shape-norm, leakage and an overall score.
- [Brilliance](https://digitalgemology.com/learn/glossary/brilliance): Brilliance is the white light that a cut stone returns to the viewer. In our census, it is the share of entering light that leaves through the crown toward the viewer.
- [Crown angle](https://digitalgemology.com/learn/glossary/crown-angle): The crown angle is the slope of the bezel facets, measured against the plane of the girdle.
- [Pavilion angle](https://digitalgemology.com/learn/glossary/pavilion-angle): The pavilion angle is the slope of the pavilion mains, measured against the plane of the girdle.

## Learn more

- [Cut Performance Wheel and cut-page scores](https://digitalgemology.com/about/how-we-measure/performance-wheel)
- [T73 Round Brilliant Cut](https://digitalgemology.com/cuts/t73-round-brilliant)
- [Cut Grading Tool](https://digitalgemology.com/about/how-we-measure/cut-grading-tool)

[All 328 terms](https://digitalgemology.com/learn/glossary)