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Fancy Shapes

Procedures Used To Calculate The Value Of Fancy Shape Diamonds

(A) Measurements and Weights: (1) Let us take as an example a pear shape diamond. When measuring the measurements of a fancy shape diamond, first you would need to measure the length, width and depth of the diamond. You can do this by using a Leveridge Gauge or a Millimeter Screw Micrometer which we discussed under Grading Mounted Diamonds. In our example of the pear shape diamond, the Length is 6.32 mm, the width is 4.30 mm and the depth is 2.43 mm. The next step would be to calculate the length-to-width ratio. In our example the length-to-width ratio is 1.47:1. (Length 6.32 mm divided by width 4.30 mm = 1.47 mm). With the depth at 2.43 mm you get a length-to-width ratio of 1.47:1. (2) To establish the weight of the diamond, weigh the stone using an electronic diamond scale. If the diamond is mounted, use the weight estimation procedures we outlined under Grading Mounted Diamonds. In our pear shape example above the pear shape diamond weighs 0.41 carats. Length X Width X Depth X .00615 Adjustment Factor (Length to Width Ratio 1.25 : 1.00). (Length 6.32 mm X Width 4.30 X Depth 2.43 X .00615 Adjustment Factor = 0.41 carats).

(B) Clarity and Plotting: (1) The clarity grading for fancy shape diamonds is the same as for rounds, but use caution. Inclusions may be lost in reflection areas near the ends of the stone. (2) Plotting fancy shape diamonds is done the same way as for rounds.

(C) Color: Color grading for fancy shape diamonds is done the same way as for round diamonds. The color grade is best determined by observing the stone in a diagonal direction. However, if a darker color is observed face-up, the color grade should be adjusted accordingly.

(D) Proportions: Use the Fancy Shapes Proportion Deductions Charts below as a guide for deductions. (1) Table Percentage: Measure the table width of the stone using the following formula. Table Width (mm) divided by Stone Width (mm) X 100 = Table Percentage. (2) Crown Angle: Estimate the crown angle by using the Profile Method we discussed under Cut. Specific angles are not required. Use a description such as shallow, very shallow, slightly shallow, normal, steep and so on. (3) Girdle Thickness: This is judged by the same criteria as round diamonds, but do not deduct for thicker girdles at the points of brilliant cuts or the clefs of heart shape diamonds. (4) Total Depth percentage: To determine the total depth percentage use the following formula. Depth (mm) divided by Width (mm) X 100 = Total Depth Percentage. If the Total Depth percentage is less than 55% or more than 65%, examine the stone carefully for a pavilion that is either too shallow or too deep. Even if the Total Depth Percentage is within this range, check the pavilion depth carefully. (5) Pavilion Depth: Examine the profile of the diamond and decide if the pavilion depth is acceptable, slightly shallow or deep, noticeable shallow or deep, obviously shallow or deep. Record the results of your observation. Now examine the stone face-up and assess the relative brilliance. If analyzing a brilliant cut, consider the size and darkness of the "Bow-Tie". An emerald cut should be examined for a prominent bulge in the pavilion. Based on these observations, determine an appropriate deduction from the Fancy Shapes Proportion Deductions Charts below, if required. (6) Culet Size: Judge the culet width of the diamond. If the culet is unattractively long, consider a deduction for this. Record your observations and deduct if necessary. (7) Major Symmetry: You should take a deduction if (a) The table or culet are appreciably off-center. (b) The girdle outline is not balanced, is unsymmetrical, or lopsided. (c) The table is not parallel to the girdle, or the diamond has a wavy girdle. (d) The culet is positioned unattractively in pears or hearts. (8) Shape Outline: Examine the stone face-up and assess the relative appeal and beauty of the shape. Consider high shoulders, flat and straight wings, squarish oval shapes and the like. Personal preference is your best guide. If the shape is appealing, take no deduction, if you feel that the shape is not as attractive as it could be, select what you feel is an appropriate deduction. Do not deduct for shape outline if you took a deduction for an unbalanced girdle outline. (9) Length-to-Width Ratio: Deduct if the diamond is too long or too short. Use the following chart as a guide only.

 

Shape Length/Width Ratio Deduction
Pear Less Than 1.25:1

1.25:1

1.50:1 to 1.75:1

2.00:1

More Than 2.00:1

10%

5%

0%

5%

10%

Marquise 1.25:1

1.50:1

1.75:1 to 2.25:1

2.50:1

3.00:1

10%

5%

0%

5%

10%

Emerald Cut and Oval Less Than 1.25:1

1.25:1

1.50:1 to 1.75:1

2.00:1

More Than 2.25:1

10%

5%

0%

5%

10%

Heart 1:1 to 1.25:1

More Than 1.25:1

0%

5%

Although deductions may be made for both shape outline and length-to-width ratio, the grader should determine if the total of the two deductions is excessive. (E) Finish: (1) Polish: Grading the polish for fancy shape diamonds is done the same way as for rounds. (2) Minor Symmetry: Grading minor symmetry for fancy shape diamonds is done the same way as for rounds, with addition of crooked keel line. (F) Total All Deductions: Total all the deductions you have determined for the above grading procedures. (G) Using the Actual Weight of the diamond select the appropriate Base Price of the diamond. Refer to the Rapaport Diamond Report. (H) Calculate and Record the Actual Base Price: Use the following formula. Base Price X (100% - Total Deductions) = Adjusted Base Price. Round to the nearest dollar. (I) Clarity/Color Percentage Value: Determine the percentage of value for clarity and color at actual weight. Refer to the Rapaport Diamond Report. (J) Calculate and Record the Stone Value: Adjusted Base Price X Percentage Value X Actual Weight = Stone Value. Round to the nearest dollar. (K) Calculate and Record the Per Carat Value: Stone Value divided by Actual Weight = Per Carat Value. Round to the nearest five dollars.

Fancy Shapes Suggested Proportion Deductions

TABLE PERCENTAGE

DEDUCT

39% or less 15%
40% - 41% 10%
42% - 43% 8%
44% - 45% 6%
46% - 47% 4%
48% - 49% 2%
50% - 58% 0%
59% 1%
60% 2%
61% 3%
62% 4%
63% 5%
64% 6%
65% 7%
66% 8%
67% 9%
68% 10%
69% 11%
70% 12%
71% or more 13%

 

GIRDLE THICKNESS

DEDUCT

Extremely Thin 4%
Very Thin 2%

Thin to Medium

0%
Slightly Thick 1% to 2%

Thick

3% to 4%
Very Thick 5% to 6%

Extremely Thick

7% to 10%

 

CROWN ANGLES

DEDUCT

Slightly Shallow 3%
Obviously Shallow 5%

 

PAVILION DEPTH

DEDUCT

Slightly Shallow or Deep

3%

Noticeably Shallow or Deep

5%

Obviously Shallow or Deep

10%

 

 

CULET

DEDUCT

None 0%
Small 0%
Medium 0%
Slightly Large 1%
Large 2%
Very Large 3%
Extremely Large 4%

 

MAJOR SYMMETRY

DEDUCT

Table or Culet Appreciably Off-Center 3% to 5%
Girdle Outline Not Balanced 5% to 10%
Table Not Parallel to Girdle or Wavy Girdle 3% to 5%
Culet Placement: Culet Positioned Unattractively 3% to 5%

 

SHAPE

DEDUCT

Ratio of Length-To-Width Too Long or Too Short 5% to 10%
Shape Outline: Unattractive Girdle Outline 5% to 10%

These suggested deductions for proportion variations encountered in fancy shape diamonds are presented only as a guide. When considering an element of proportioning, always base the deduction on the visual effect created by the variation. It is correct to adjust the deduction to a lower percentage if you feel the proportion variation has not affected the beauty or appeal of the stone as much as the suggested deduction indicates.

Affordable advertising rates - Drive customers to your business - Build powerful brand recognition - Global exposure leads to a successful business Affordable advertising rates - Drive customers to your business - Build powerful brand recognition - Global exposure leads to a successful business Affordable advertising rates - Drive customers to your business - Build powerful brand recognition - Global exposure leads to a successful business

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