| GemCad Ray Traces for RI = 1.76 | ||
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||
| 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.
