Twelve questions about the whole course, then a picture round with four pictures. Questions 11 and 12 combine lessons. Answer all the questions first. The answers are below the line, and never on the pictures.
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.
Questions
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Question 1: Why does GIA's color scale start at D and not at A?
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b: The creators wanted no link to the older systems, which people used loosely (lesson 1).
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Question 2: A diamond weighs 0.75 ct. How many points is that, and how many milligrams?
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b: The carat has 100 points and 200 mg: 0.75 × 200 = 150 mg (lesson 2).
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Question 3: In the simulator, you go from 1 ct to 2 ct. The stone stays the same size on screen. Where do you read how much bigger it really is, and about how much bigger is it?
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In the scale bar and in the measurements in the report. It is about 26% wider, 6.48 to 8.16 mm, because weight grows with the cube of size (lesson 2).
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Question 4: Which statement about fluorescence is correct?
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b: About 25 to 35% of diamonds fluoresce, and more than 95% of those glow blue. For most, it makes no difference you can see in daylight (lesson 4).
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Question 5: A diamond has more yellow than the Z master stone. What happens to its grading?
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b: Past Z, a diamond is treated as a colored diamond, and a strong enough color gets a fancy grade (lesson 4).
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Question 6: Two diamonds each have three inclusions. One is VS2, the other SI2. Give three things, other than the number, that can explain the difference.
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Any three of: the size of the inclusions, their type, their position (under the table or near the girdle), how noticeable they are in the whole stone, and how dark they look (lesson 5).
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Question 7: On the light map in the simulator, what does black show? And what happens to it when the T73 goes from Excellent to Poor?
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Leakage: light that goes out through the pavilion and does not return to your eye. It grows from 4% at Excellent to 45% at Poor, as the pavilion gets steeper (lesson 6).
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Question 8: A diamond has Excellent proportions, Very Good polish and Fair symmetry. What is the best cut grade it can get?
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c: Fair symmetry caps the cut grade at Good. Very Good polish alone still allows Excellent (lesson 7).
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Question 9: Which statement about facets is correct?
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b: The proportions, polish and symmetry decide the brightness (lesson 6).
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Question 10: Under the Restaurant lighting in the simulator, a D and an H look the same. A friend says "color grades don't matter". What is right and what is wrong about that?
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Right: warm, dim light hides small color differences, so the look of a stone depends on the light. Wrong: in neutral light, and against master stones, the difference is real. That is why labs grade color in a standard environment (lesson 3).
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Question 11: Two stones for a ring: a 0.99 ct, G, VS2, Excellent cut, and a 1.00 ct, J, SI2, Good cut. Compare them one C at a time. Which differences can you see, and which show up mostly on paper or at 10x?
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Carat: 0.01 ct makes 0.02 mm, and nobody can see that. Color: G and J are both near colorless and look white face up; J may show a slight warmth beside a G. Clarity: graders find most VS2 and SI2 inclusions at 10x, but you can sometimes see SI2 by eye. Cut: Excellent against Good changes the whole face, and the Good stone has more leakage. So the visible difference is mostly cut. Also, the 0.99 usually costs less than the round 1.00 (lessons 2, 3, 5, 6 and 8).
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Question 12: A seller offers a 1.00 ct, D, Flawless round, "the best grades money can buy". But the paperwork has no cut grade. In the simulator, the same grades at a Poor cut measure 6.2 mm across and leak 45% of the face. What do you ask before you buy, and why?
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Ask for the proportions or a full report with a cut grade, or look at the stone in several lights. Color and clarity tell you nothing about how the stone handles light. A poorly cut 1.00 ct faces up like an Excellent 0.86 ct and can leak nearly half its face. So the "best grades" may still look worse than a well-cut stone with lower grades (lessons 6, 7 and 8).
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Picture round
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Question 13: Which stone has the higher color grade? About how far apart are they on the D-to-Z scale? (lesson 3)
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Stone 2, a G (near colorless), against stone 1, an M (faint): six letters apart. The M shows a warm tint under the neutral lamp; the G looks white (lesson 3).
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Question 14: One of these is I2. Which one? Can you put the other two in order at this distance? (lesson 5)
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A is the I2: you can see dark crystals without magnification. B is Flawless and C is SI1. At this distance they can look the same, and that is why graders judge clarity at 10x (lesson 5).
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Question 15: These are the same design at three cut grades. Put them in order from best to worst, and say what you used to decide. (lesson 6)
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B, C, A: B is Excellent (mostly red and blue, almost no black). C is Good (a dark ring opens around the table). A is Poor (the whole outer band leaks). Read the black: leakage (lesson 6).
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Question 16: These two stones are different in one C only. Which C, and which stone is better? (lessons 1, 6)
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Cut: stone 2 is the same stone cut to Fair, with a wider table and a flatter, washed-out face. Stone 1, Excellent, is the better stone. Color and clarity are the same, and both weigh 1.00 ct (lessons 1 and 6).
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Your score
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.