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Diamond Essentials > 4 - Cut and Value > Flashcards

4 - Cut and Value Flashcards

1
Q

Proportion

A

The angles and relative measurements of a polished gem, and their relationships to each other.

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2
Q

Finish

A

The quality of the polish and the precision of the cut (symmetry.)

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3
Q

Make

A

The qualities of a faceted diamond’s proportions and finish.

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4
Q

Brilliance

A

Light reflected off the surface of a diamond.

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5
Q

Refraction

A

The change in speed and possible change in direction of light as it travels from one transparent material to another.

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6
Q

How does refraction occur in a diamond?

A

Refraction occurs when light enters a diamond, slows down, travels at a different angle, and strikes the interior surface.

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7
Q

Once light has struck an interior surface of a diamond, where does it go?

A

It either continues to reflect or exits the diamond.

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8
Q

Refractive Index (RI)

A

A measure of the change in the speed and angle of light as it passes from one material to another.

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9
Q

Dispersion

A

The separation of white light into its spectral hues.

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10
Q

What is fire the result of?

A

Dispersion

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11
Q

Scintillation

A

The flashes of white and spectral-colored light as the light, observer, or diamond moves.

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12
Q

What are the objectives of a planner and what do they look at?

A

A planner has to maximize carat weight and determines this yield by inspecting structure and interior features.

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13
Q

Blocking stage

A

When a diamond gets its first 17-18 facets and establishes initial symmetry.

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14
Q

What proportion measurement is checked during cutting?

A

Pavilion angle

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15
Q

Brillianteer

A

Someone who polishes the final facets on the diamond.

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16
Q

When does the girdle become polished or finished?

A

It is one of the last steps in the polishing process.

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17
Q

Girdle outline

A

A diamond’s face-up shape.

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18
Q

What kind of shape is more dependent on girdle outline?

A

Fancy.

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19
Q

Shoulder

A

One of the two sides adjacent to the rounded end of a pear or oval shape.

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20
Q

Wing

A

One of the two sides near the point of a marquise, pear, or heart.

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21
Q

Table size

A

Table size expressed as a percentage of the average girdle diameter.

For round brilliants.

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22
Q

Average girdle diameter (AGD)

A

The result achieved by averaging the smallest and largest girdle measurements of a round brilliant.

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23
Q

What basic measurement is used in many proportion calculations?

A

Average girdle diameter.

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24
Q

Crown angle

A

The angle formed by the bezel facets and the girdle plane.

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25
Q

At what crown angle do diamonds become more susceptible to damage?

A

Shallower than 25 degrees.

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26
Q

How is girdle thickness judged?

A

By eye.

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27
Q

What are the visual consequences of a thick girdle?

A

Large, fuzzy, grey reflections. May make stone appear dark. Occasionally enhances a fancy-colored diamond.

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28
Q

Where should girdle thickness vary in a round, oval, or cushion brilliant?

A

The thickness should be thinner between pairs of mains and half facets, and thicker where the points of the crown and pavilion main facets meet.

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29
Q

Why is it good to vary the girdle thickness?

A

It can prevent chipping at points.

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30
Q

How should an unpolished girdle appear? How should it not appear?

A

Should be frosty and waxy, faceted, or polished. It should not be rough and granular.

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31
Q

Pavilion depth

A

The distance from the bottom of the girdle plane to the culet, expressed as a percentage of the AGD.

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32
Q

To what light features is pavilion depth critical?

A

Brightness and fire.

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33
Q

Fisheye

A

When the girdle reflection forms an unattractive gray ring and gives a dull, flat look.

34
Q

When does a fisheye occur?

A

When the pavilion depth <38%, or has a normal 40% depth with a large table.

35
Q

At what pavilion depth will a gem usually look dark in center?

A

Deeper than 49%.

36
Q

Nailhead

A

A dark area under the entire table.

37
Q

What is a nailhead caused by?

A

A pavilion depth of 50% or more.

38
Q

Pavilion angle

A

The angle formed by the pavilion main facets and the girdle plane.

39
Q

Dark bow-tie

A

Appears as described under table.

40
Q

How can a dark bow-tie be mitigated?

A

Can balance light display with an elongated culet or with changing the pavilion angle.

41
Q

Pavilion bulge

A

Larger-than-usual pavilion angle on the middle tier of facets designed to add weight to a step cut stone.

42
Q

What are the difficulties of a pavilion bulge?

A

Can reduce brilliance, become more difficult to set.

43
Q

Total depth

A

Table-to-culet depth, expressed as a percentage of AGD. Combines crown height, girdle thickness, and pavilion depth.

44
Q

What does a total depth of <55% indicate?

A

Shallow crown or pavilion.

45
Q

What does a total depth of >65% indicate?

A

Crown or pavilion might be deep and the girdle is probably thick.

46
Q

How is culet size determined?

A

It is visually inspected.

47
Q

What is the purpose of the culet?

A

To protect the bottom of the gem against accidental chipping.

48
Q

How can one see a medium culet?

A

Under 10x, not with the naked eye.

49
Q

How can one see a large culet?

A

With the naked eye, easy to spot without magnification.

50
Q

Length-to-width

A

Ratio of a fancy shaped diamond.

51
Q

What is the typical L:W ratio of a marquise?

A

1.75:1 - 2.25:1

52
Q

What is the typical L:W ratio of an oval?

A

1.33:1 - 1.66:1

53
Q

What is the typical L:W ratio of an emerald cut, rectangular cushion, or pear?

A

1.5:1 - 1.75:1

54
Q

What is the typical L:W ratio of a heart?

A

1:1

55
Q

What is the ideal table size of a round brilliant?

A

50-66%

56
Q

What is the ideal crown angle of a round brilliant?

A

25-35 degrees

57
Q

What is the ideal pavilion depth of a round brilliant?

A

42-44%

58
Q

What characterizes the pavilion depth of a small stone?

A

Usually deep.

59
Q

In what case would a cut gem carry up to 10% of its weight in its girdle?

A

In the case of a small stone, where shape is not as much of a concern.

60
Q

What is the ideal table size of an emerald cut?

A

> 70%

61
Q

What is the ideal pavilion depth of a fancy shape?

A

50% or more

62
Q

How are proportions useful to an appraiser?

A

They can yield accurate weight measurements with the correct tools and formulas.

63
Q

Polish

A

The overall condition of the facet surfaces of a finished diamond.

64
Q

What are the polish grades?

A

Excellent, Very Good, Good, Fair, Poor

65
Q

What does an “excellent” polish grade mean?

A

“Superior” with very few hard-to-find blemishes.

66
Q

What does a “very good” polish grade mean?

A

Faint polish lines or inconspicuous minor polish features.

67
Q

What does a “good” polish grade mean?

A

Noticeable white polish features.

68
Q

What does a “fair” polish grade mean?

A

Obvious polish features.

69
Q

What does a “poor” polish grade mean?

A

Obvious polish features that reduce overall transparency.

70
Q

Symmetry

A

The exactness of a finished gem’s shape and the placement of facets.

71
Q

List 8 common symmetry variations.

A

Table or culet off-center
Girdle outline out-of-round
Facets that fail to point properly
Misaligned crown and pavilion facets
Table is not a regular octagon
Misshapen facets
Extra facets
Uneven outline

72
Q

What are the grades for symmetry?

A

Excellent, Very Good, Good, Fair, Poor

73
Q

What goes into a cut grade?

A

Polish, symmetry, proportion, and light features.

74
Q

Light features (personal)

A

Brilliance, fire, fluorescence, transparency, and scintillation.

75
Q

Design

A

A diamond’s physical shape, including its proportion and durability, determined by decisions made in the fashioning process.

76
Q

Craftsmanship

A

The care that goes into the fashioning of a polished diamond, as confirmed by its finish.

77
Q

What cut has excellent light features?

A

Round brilliant or triangular brilliant.

78
Q

What is a selling point of an oval diamond?

A

They often look larger than round diamonds of the same carat weight.

79
Q

What are some selling points of a marquise?

A

Can compliment long fingers and can appear larger than round diamonds of the same carat weight.

80
Q

When would you recommend a princess cut?

A

As an alternative to emerald cut to those who like brilliant cuts.

81
Q

What qualities would you emphasize with an emerald cut?

A

Elegance, and transparency.

Diamond Essentials (5 decks)

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