The history of the brilliant · lesson 4

The old mine: tidier, not brighter

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

Five questions on lesson 4 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 changed in diamond supply in the 1720s?

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    b: Brazil (1725 or 1728, depending on the source).

  2. Question 2: According to Tolkowsky, how did the triple cut change into the old mine?

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    b: Still by hand; the machine came in the 1870s.

  3. Question 3: Which score improves from the Peruzzi to the old mine, and which falls the most?

    Show our answer

    Symmetry improves (85 → 90); brilliance falls the most (75 → 59).

  4. Question 4: Why does scintillation stay at 81?

    Show our answer

    The facet count doesn't change: 74 in both models.

  5. Question 5: A friend says, "It's rounder and more even, so it must be brighter." What do you tell them?

    Show our answer

    Neatness is craftsmanship. Brightness depends on the angles, and nobody calculated those. The old mine leaks 32% of its light.

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