Design

Pentalume Sapphire

A 51-facet clipped pentagon for sapphire, designed by Niklas Gussek.

Download .psdd GemCAD .asc Gem Cut Studio .gcs Cutting instructions (PDF)

1The design

Five broad blue sectors, protected corners and paired shoulder facets. Cut in sapphire with the c-axis normal to the table.

Designer: Niklas Gussek
Shape: Clipped pentagon, L/W 1.051
Facets: 51 in 9 tiers: 20 pavilion, 10 girdle, 20 crown and the table
Symmetry: 5-fold, mirror
Index gear: 80
Material: Sapphire, RI 1.768
Crystal axis: Through the table
Size: 10.00 × 10.51 × 6.22 mm (width × length × depth)
Weight: 4.31 ct in sapphire at this size (10.00 mm wide). It scales with the cube of the width: 2.20 ct at 8 mm, 0.93 ct at 6 mm.

Pentalume Sapphire seen at an angle — Fig. 1 — Seen from 74° above the girdle, Daylight lighting, 2048 samples per pixel. Rendered with Pleochroma.

2Renders

The stone in the built-in Sapphire material, rendered by Pleochroma’s spectral path tracer at 2048 samples per pixel: from above and from the side at one scale, then face-up under two more of the app’s lighting setups and tilted by 10°. In the Light Tent and under Shop Lights the dark center is the camera and the observer, mirrored in the table.

Pentalume Sapphire from above and from the side — Fig. 2 — From above and from the side at one scale, Daylight.

Pentalume Sapphire face-up in the Light Tent — Fig. 3 — Face-up, Light Tent.

Pentalume Sapphire face-up under Shop Lights — Fig. 4 — Face-up, Shop Lights.

Pentalume Sapphire tilted by 10 degrees — Fig. 5 — Tilted 10°, Daylight.

3Tilt video

The stone rocking about two of the tilt chart’s axes in turn, 0° and 90°, from Pleochroma’s tilt video export.

Fig. 6 — Tilt video, 1024 × 1024, 10 s.

4Facet angles

Angles and index positions on an 80-tooth index gear, in cutting order, written as the standard cutting-instructions sheet writes them. Every facet’s exact depth is in the design files; the cutting instructions (PDF) add the meet for every tier.

Crown view with the facet labels and index positions — Fig. 7 — Crown, profile, end and pavilion, from the cutting instructions Pleochroma writes for the design. Click a view for 1600 × 1257 pixels.

Tier	Angle	Index	Description
Pavilion
P1	43.00°	80-16-32-48-64	Five broad mains
P2	40.50°	08-24-40-56-72	Five corner guards
P3	44.00°	76-04-12-20-28-36-44-52-60-68	Ten shoulder splits
Girdle
G1	90.00°	80-16-32-48-64	Five long sides
G2	90.00°	08-24-40-56-72	Five clipping flats
Crown
C1	34.00°	80-16-32-48-64	Five broad bezels
C2	30.00°	08-24-40-56-72	Five corner bezels
C3	33.00°	76-04-12-20-28-36-44-52-60-68	Ten shoulder facets
Table	0.00°	–	The table

5Proportions and light

Table: 53.6 % of the width
Crown height: 14.4 % (C/W 0.144)
Pavilion depth: 43.8 % (P/W 0.438, P/C 3.033)
Girdle: 4.0 %
Total depth: 62.2 % (H/W 0.622)
Volume: V/W³ 0.215

Light figures in sapphire under the ISO hemisphere lighting, table up and averaged over the tilt sweep, as Pleochroma computes them. They are fractions of light paths, not a measured light return.

	Brilliance	Windowing	Extinction	Fire index	Scintillation
Table up	84.8 %	2.3 %	12.9 %	28.9	24.1 %
Tilted	47.8 %	39.2 %	13.0 %	–	–

6Downloads

File	Format	Opens in	Size
Pentalume_Sapphire.psdd	Pleochroma design	Pleochroma Cut, the web app and the mobile app. Keeps the material (Sapphire), the size (10 mm) and the crystal axis.	2.9 KBSHA-256 78ec1fd2d209c4d228ae62371dd05df6ec9c10deafb9588effb72dec45a38899
Pentalume_Sapphire.asc	GemCAD 5.0	GemCAD and the faceting programs that read its files. Geometry and angles only: choose Sapphire, 10 mm and the c-axis through the table yourself.	0.6 KBSHA-256 7e0bb1330e2c2de0bd66c7db7d102caf013393ba9e4a9dbb9d99cfbab99c9f29
Pentalume_Sapphire.gcs	Gem Cut Studio 1.1	Gem Cut Studio. Geometry, angles and the refractive index of sapphire.	34.1 KBSHA-256 890f25be7afb437c4afa65c2031ea27b37e892da570fd387b03e8276efbcad6e
Pentalume_Sapphire.pdf	Cutting instructions (PDF)	Any PDF viewer; prints on US Letter. The standard cutting-instructions sheet with the four views, angles, indices and the meet for every tier.	27.5 KBSHA-256 c9d6145028b2d16791f7a59e2cfe1d668b12985c8ee3c79d4587c88b5f0eb4fb

The three design files hold the same geometry; the PDF is the cutting-instructions sheet for printing. A .psdd file opens in Pleochroma Cut and in the web app, with the renders, the cutting instructions and the cutting mode.