Christmas Oval 2001
GemCad Ray Traces for RI = 1.76
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".


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