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