| GemCad Ray Traces for RI = 1.76 | ||
 |
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| Random Model | Cosine Model | ISO Model |
| Christmas Oval 2001
Computed 11-13-01 by Jim Perkins jperkins@medina.ohio.net |
|
| Angles for R.I. = 1.76 | 57 facets + 16 facets on girdle = 73 |
| 2-fold, mirror-image symmetry | 96 index |
| L/W = 1.245 T/W = 0.680 T/L = 0.546 P/W = 0.463 C/W = 0.143 | H/W = (P+C)/W+0.02 = 0.626 P/H = 0.740 C/H = 0.228 |
| Vol./W^3 = 0.262 | Brightness at 0 degrees tilt for RI = 1.76
COS = 70.6 ISO = 87.9 |
| Pavilion | |||
|---|---|---|---|
| G1 | 90.00 | 02-46-50-94 | GRIND TO WIDTH |
| A | 43.50 | 02-46-50-94 | TCP LEVEL GIRDLE |
| B | 41.59 | 08-40-56-88 | TCP @ CULET |
| C | 39.98 | 13-35-61-83 | TCP @ CULET |
| D | 37.56 | 21-27-69-75 | TCP @ CULET |
| G2 | 90.00 | 08-40-56-88 | LEVEL TO G1 |
| G3 | 90.00 | 13-35-61-83 | LEVEL TO G2 |
| G4 | 90.00 | 21-27-69-75 | LEVEL TO G3 |
| E | 42.80 | 96-48 | MP @ GIRDLE, PCP |
| F | 40.08 | 10-38-58-86 | MP @ GIRDLE, PCP |
| H | 36.51 | 24-72 | MP @ GIRDLE, PCP |
| Crown | |||
| 1 | 37.00 | 02-46-50-94 | GRIND TO THICKNESS, LEVEL GIRDLE |
| 2 | 34.62 | 08-40-56-88 | LEVEL GIRDLE TO 1 |
| 3 | 35.00 | 13-35-61-83 | LEVEL GIRDLE TO 2 |
| 4 | 31.47 | 21-27-69-75 | LEVEL GIRDLE TO 3 |
| 5 | 32.30 | 96-48 | MP @ GIRDLE |
| 6 | 29.93 | 10-38-58-86 | MP @ GIRDLE |
| 7 | 26.83 | 24-72 | MP @ GIRDLE |
| 8 | 20.36 | 05-43-53-91 | MP @ 1 & 2 |
| 9 | 17.56 | 17-31-65-79 | MP @ 3 & 4 |
| T | 0.00 | Table | MP @ 5, 6 & 7 |
I computed this spiked oval for my youngest daughter Betsy's Christmas gift. In order to create Christmas Oval 2001 I started with data found in Long & Steele Volume 1 Facet Designs OVALS. I entered the facet particulars into GemCad using Long & Steele's specifications for a crown and pavilion I liked. I fixed a couple of meet point problems and then using the tangent ratio function I adjusted facet angles until I achieved the desired optical performance (to sparkle like Rudolf's nose of course) and the physical profile I desired.
I think Christmas Oval 2001 makes a nice oval brilliant for the intended gem material. I am cutting a couple of ring size stones for my daughters using this design for Christmas this year, hence my "tag".
