Allan's Challenge

by Arya Akhavan (March 2015)
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Gemology Projectopen
L/W
—
Design RI
1.54
H/W
—
Gear
96
V/W³
—
Symmetry
1 (mirrored)
Facets
89
Tiers
31
Crown
31
Pavilion
58

This design was written for Allan Aoyama, who asked me a year ago to help him come up with an interesting pear-shaped design with a unique step pavilion and brilliant crown. We posted this to the Gemology Online forums' "From the GPU" section, where users can submit requests, and this was my take on it. Works in materials from quartz to zircon (RI = 1.54 - 1.93) with no changes, but designed for tanzanite.

Wireframe

Allan's Challenge 3D view
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Pavilion

#AngleFacetsNotes
G190.00°
24324048566472
Set stone size.
G290.00°
2076
Level girdle.
G390.00°
1581
Meet P2, P3, G2
G490.00°
1383
Level girdle.
P1145.91°
24324048566472
Cut even step to 1/3.
P1445.65°
1581
Meet P8, P9, P13; level girdle.
P1244.91°
2076
Meet P6, P7, P11; level girdle.
P644.90°
24324048566472
Cut even step to 1/3.
P944.64°
1581
Meet P3, P4, P8
P1344.02°
1977
Meet P7, P8, P12
P743.91°
2076
Meet P1, P2, P6
P143.91°
24324048566472
Cut to centerpoint.
P443.65°
1581
Level girdle.
P1543.49°
1383
Meet P9, P10, P14; level girdle.
P843.02°
1977
Meet P2, P3, P7
P242.91°
2076
Meet at culet.
P1042.49°
1383
Meet P4, P5, P9
P342.02°
1977
Meet at culet.
P541.50°
1383
Meet P3, P4

Crown

#AngleFacetsNotes
C338.00°
1581
Level girdle.
C138.00°
24324048566472
Set girdle width.
C438.00°
1383
Level girdle.
C734.51°
1482
Meet G3, G4, C3, C4
C234.00°
2076
Level girdle.
C532.00°
283644526068
Meet G1, C1
C631.34°
1779
Meet G2, G3, C2, C3
C1030.79°
1680
Meet C3, C6, C7
C929.00°
2274
Meet C1, C2, C5
C826.00°
324864
Meet C1, C5
T0.00°
T0.00°
24
Meet 4x unique meetpoints.