PentaStar
GemCad Ray Traces for RI = 1.76
Random Model Cosine Model ISO Model
PentaStar
designed by Bob Keller 11.19.01
A Cut Corner Pentagon with Pavilion Star for Synthetic Corundum
Angles for R.I. = 1.76 56 facets + 10 facets on girdle = 66
5-fold, mirror-image symmetry 120 index
L/W = 1.051 T/W = 0.656 T/L = 0.624 P/W = 0.480 C/W = 0.166 H/W = (P+C)/W+0.02 = 0.665 P/H = 0.721 C/H = 0.249
Vol./W^3 = 0.250 Brightness at 0 degrees tilt for RI = 1.76
COS = 74.6 ISO = 85.5
Pavilion
1 75.00 120-024-048-072-096 Establish lower girdle line, match g1
2 43.00 012-036-060-084-108 Meet g1.g2.1
3 43.00 006-018-030-042-054-066-078-090-102-114 Meet 1.g1.g2.2
4 41.00 008-016-032-040-056-064-080-088-104-112 Meet 3.2.3, culet
Crown
a 72.00 120-024-048-072-096 Level upper girdle line, match g1
b 40.00 006-018-030-042-054-066-078-090-102-114 Meet a.g1.g2
c 23.90 120-024-048-072-096 Meet b.a.b
d 40.36 012-036-060-084-108 Meet a.b.g2.g1, b.c.c.b
t 0.00 Table Meet c.b.d

PentaStar CAM Preform
pf1 45.00 120-024-048-072-096 Cut to temporary center point
g1 90.00 120-024-048-072-096 Match pf1, make level temporary girdle
pf2 40.41 012-036-060-084-108 Meet pf1 at centerpoint
g2 90.00 012-036-060-084-108 Meet pf1.pf2.g1

The PentaStar GemCad Design File and PentaStar GemCad Preform Design File are available for GemCad users.

Index of Gem Designs

Perfect Transfer Index

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© Bob's Rock Shop Bob Keller