Hexidec by Paul A. Head

GemCad Ray Traces for RI = 1.54
Random Model	Cosine Model	ISO Model

Hexidec - Designed by Paul A. Head headbnk@azstarnet.com ©1995
Angles for R.I. = 1.54	129 facets + 16 facets on girdle = 145
16-fold, mirror-image symmetry	96 index
L/W = 1.000 T/W = 0.503 T/L = 0.503 P/W = 0.450 C/W = 0.146	H/W = (P+C)/W+0.02 = 0.616 P/H = 0.731 C/H = 0.236
Vol./W^3 = 0.201	Brightness at 0 degrees tilt for quartz Cos = 86.0% ISO = 91.5%

Pavilion
P1	42.00	01-05-07-11-13-17-19-23-25-29-31-35-37-41-43-47-49-53-55-59-61-65-67-71-73-77-79-83-85-89-91-95	Cut to Common Center Point
G1	90.00	96-06-12-18-24-30-36-42-48-54-60-66-72-78-84-90	Set width of stone.
P2	43.00	96-06-12-18-24-30-36-42-48-54-60-66-72-78-84-90	Meet G1-G1-P1;makes level Girdle.
P3	41.50	96-06-12-18-24-30-36-42-48-54-60-66-72-78-84-90	Meet P1-P1-P2,forms new CCP.
Crown
C1	31.00	96-06-12-18-24-30-36-42-48-54-60-66-72-78-84-90	Match G1; Leave 2% of W for girdle.
C2	30.1	01-05-07-11-13-17-19-23-25-29-31-35-37-41-43-47-49-53-55-59-61-65-67-71-73-77-79-83-85-89-91-95	Meet G1-G1-C1 at Girdle.
C3	29.00	96-06-12-18-24-30-36-42-48-54-60-66-72-78-84-90	Meet C1-C2-C2
	0.00	Table	Meet C2-C2-C3-C3

GemCad users can download a zipped .gem design file for Hexidec: hexidec.zip.

I have cut a 22.8 mm topaz from this design with no difficulty but would not want to try a 10 mm size. Note that the angles shown are not given for any particular R.I. - you will need to tangent ratio them as appropriate for the R.I. of the material you select. This design is both simple and easy to cut.

Recommended Hexidec Angles for Other Refractive Indexes
R.I. = 1.62 P1 40.5 P2 41.5 P3 40.0 C1 32.0 C2 31.1 C3 30.0 P/W = 42.7% C/W = 15.1% ISO = 92.2%	R.I. = 1.76 P1 41.0 P2 42.0 P3 40.5 C1 42.0 C2 41.0 C3 39.7 P/W = 43.5% C/W = 21.8% ISO = 90.2%	R.I = 1.76 P1 36.5 P2 37.4 P3 36.0 C1 41.0 C2 40.0 C3 38.7 P/W = 37.0% C/W = 21.0% ISO = 87.6%	R.I. = 2.15 P1 32.5 P2 33.4 P3 32.0 C1 44.0 C2 43.0 C3 41.7 P/W = 31.8% C/W = 23.4% ISO = 94.8%	R.I = 2.15 P1 42.0 P2 43.0 P3 41.5 C1 37.0 C2 36.0 C3 34.8 P/W = 45.1% C/W = 18.2% ISO = 92.0%

The dual choices for R.I. 176 and 2.15 are because the ISO brightness contour maps have two high value ridges. I have not picked the absolute highest ISO values but have hedged toward higher crowns to enhance the effects of dispersion.

Enjoy cutting your Hexidec!

[ Return to Gemstone Design Index ]