Derek

GemCad Ray Traces for RI = 1.76
Random Model	Cosine Model	ISO Model

Derek Designed by Jim Perkins 07.04.01 jperkins@medina.ohio.net
A design for my nephew Derek's birthday ring - Happy Birthday Derek from Uncle Jim & Aunt Kim.
Angles for R.I. = 1.76	73 facets + 12 facets on girdle = 85
12-fold, mirror-image symmetry	96 index
L/W = 1.000 T/W = 0.567 T/L = 0.567 P/W = 0.442 C/W = 0.130	H/W = (P+C)/W+0.02 = 0.592 P/H = 0.747 C/H = 0.219
Vol./W^3 = 0.215	Brightness at 0 degrees tilt for RI = 1.76 COS = 88.7 ISO = 95.3

Pavilion
G	90.00	96-08-16-24-32-40-48-56-64-72-80-88	Cut girdle to establish stone size./TD>
A	42.00	96-08-16-24-32-40-48-56-64-72-80-88	Cut to tcp,level girdle.
B	40.51	04-12-20-28-36-44-52-60-68-76-84-92	PCP. Meet at girdle.
Crown
1	40.02	96-08-16-24-32-40-48-56-64-72-80-88	Set girdle width, level girdle.
2	33.23	04-12-20-28-36-44-52-60-68-76-84-92	Meet at girdle.
3	19.36	96-08-16-24-32-40-48-56-64-72-80-88	Meet at facet 1 & table.
4	14.00	04-12-20-28-36-44-52-60-68-76-84-92	Meet at facet 2.
T	0.00	Table	Cut at 0 degrees, Meet at 3.

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