Twelve questions on the whole course. The last three combine lessons. Answer all of them first. The answers are below the line.
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: How many facets does a standard round brilliant have on the crown and on the pavilion?
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a: Table, 8 stars, 8 bezels and 16 upper halves on the crown; 8 mains and 16 lower halves on the pavilion (lesson 1).
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Question 2: A round's measurements read 6.40 – 6.46 × 3.98 mm. What's its total depth, roughly?
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b: Average diameter 6.43 mm; 3.98 / 6.43 = 61.9% (lesson 2).
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Question 3: What does the crown angle measure?
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a: Measured from the plane of the girdle (lesson 4).
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Question 4: You make the table larger and keep the crown angle the same. What happens to the crown height, and why?
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It falls: the crown ring around the table gets narrower, so at the same slope it rises less (lessons 3 and 4).
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Question 5: In diamond, light inside the stone meets a pavilion facet 15° from square-on. What happens, and what is the name of the limit?
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Most of it goes out through the facet, because it's within the critical angle, 24.4° in diamond. Past that limit, light reflects completely (lesson 5).
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Question 6: On the Cut Grading Tool's light map, a very shallow pavilion floods the face with blue. What does the blue show you?
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b: The contrast zone, where your own head blocks the light (lesson 5).
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Question 7: A stone's lower half length is 90%. On that alone, what's the best cut grade it can get?
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b: 90% is outside the Excellent range (70–85%) but inside Very Good (lesson 6).
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Question 8: Why might a cutter paint or dig out the half facets?
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To keep weight, sometimes to lift a stone over a carat threshold. Or to polish away an inclusion near the girdle. It costs face-up appearance and grade (lesson 6).
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Question 9: A report gives the girdle as "Thin to Slightly Thick". What do the two words describe?
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The girdle's thinnest and thickest valleys, judged by a grader at 10x (lesson 7).
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Question 10: A stone has the T73's angles but a 4.5% girdle and a Medium culet. Predict the grade and give both reasons.
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Very Good: the thick girdle pushes the total depth to about 63.6%, past 63%. And a Medium culet also limits the grade to Very Good (lessons 7, 8 and 9).
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Question 11: The T57 and the T73 have the same crown, the same pavilion and the same width. Which one weighs more, by about how much, and which one would a setter prefer?
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The T73, about 10% heavier at the same width (1.99 ct against 1.81 ct at 8.15 mm), because of its girdle band. A setter would prefer the T73: the T57's knife-edge chips easily and gives little to hold (lessons 1 and 7).
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Question 12: You see two 1.00 ct rounds. One is 6.48 – 6.48 × 4.00 mm. The other is 6.16 – 6.16 × 4.16 mm with a Large culet. Which faces up larger? Which one shows a spot in the center? And what grade limit does the culet alone put on it?
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The first faces up larger (6.48 mm, 61.7% deep). The second is narrower and about 67.5% deep, with weight below. The second also has a Large culet. Face up, it shows as a spot in the center, and it limits the grade to Good (lessons 2, 8 and 9).
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One lesson at a time
Each lesson has five questions. The questions and the answers to pick from come in a new order every time you start.