---
title: "Tolkowsky 1919: the cut that was calculated: lesson quiz"
description: "Five questions on “Tolkowsky 1919: the cut that was calculated”, lesson 6 of Digital Gemology's The history of the brilliant course, in a new order every time, with an explanation for every answer."
url: https://digitalgemology.com/skool/quiz/the-history-of-the-brilliant/tolkowsky-1919-the-cut-that-was-calculated
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[The history of the brilliant](https://digitalgemology.com/skool/quiz/the-history-of-the-brilliant#lessons) · lesson 6

# Tolkowsky 1919: the cut that was calculated

Lesson quiz · five questions, in a new order every time

Five questions on lesson 6 of The history of the brilliant. The questions and the answers to pick from come in a new order every time you start.

Pick an answer, and the question marks itself. For a question that you answer in your own words, think of your answer first. Then show our answer and say whether you had it. Nothing is saved or sent.

1. Question 1: What could a cutter do with a saw that cleaving couldn't?
  ### Show the answer
  **b**: Cleaving only works along the crystal's cleavage planes; a saw cuts where you choose.
2. Question 2: Which property of diamond did Tolkowsky's calculation start from?
  ### Show the answer
  **b**: 2.417, which gives the critical angle of 24° 26′.
3. Question 3: What was the pavilion angle meant to do, and what was the crown angle meant to balance?
  ### Show our answer
  The pavilion keeps light in: it reflects the light completely twice and sends it back up. The crown balances the amount of light against the spread of colors (brilliance against fire).
4. Question 4: Name two simplifications in Tolkowsky's model.
  ### Show our answer
  Any two of: a 2D slice, light only from straight above, at most two reflections.
5. Question 5: The T57 scores 72 for scintillation and the T73 80, with identical angles. Why?
  ### Show our answer
  The T73 has 16 girdle facets, and the Wheel counts facets for scintillation (57 → 72, 73 → 80).

## More

- Next: [Lesson 7, Hearts and arrows: precision you can see](https://digitalgemology.com/skool/quiz/the-history-of-the-brilliant/hearts-and-arrows-precision-you-can-see)
- [The The history of the brilliant quiz](https://digitalgemology.com/skool/quiz/the-history-of-the-brilliant), on the whole course
- [All The history of the brilliant lesson quizzes](https://digitalgemology.com/skool/quiz/the-history-of-the-brilliant#lessons)
- [The history of the brilliant: all the lessons](https://digitalgemology.com/learn/historic-cuts)