Four Triangles by Claude Marc-Aurčle

Four Triangles ©7-96 - designed by Claude Marc-Aurčle -
Angles for R.I. = 1.54 49 facets + 6 facets on girdle = 55
3-fold, mirror-image symmetry 96 index
L/W = 1.000 T/W = 0.450 T/L = 0.450 P/W = 0.432 C/W = 0.172 H/W = (P+C)/W+0.02 = 0.625
Vol./W^3 = 0.178 Brightness at 0 degrees tilt for quartz
COS = 70.3 ISO = 83.2

a 90.00 04-28-36-60-68-92 Establish the outline
b 52.00 04-28-36-60-68-92 Cut to temporary center point
c 46.10 05-27-37-59-69-91 Meet a-b
d 47.50 03-29-35-61-67-93 Meet a-b
e 42.00 07-25-39-57-71-89 Meet a-b-c
f 45.70 01-31-33-63-65-95 Meet a-b-d

1 45.50 04-28-36-60-68-92 Level girdle
2 33.60 02-30-34-62-66-94 Meet a-1
3 30.50 96-32-64 Meet a-1-2
4 28.50 16-48-80 Meet a-1
5 00.00 Table Meet 2-3-4

The Four Triangles design file is available for download for GemCad users: four.gem

Four Triangles Design Notes
By Claude Marc-Aurčle

The originality of this design lies in the crown's layout. Its triangular table is surrounded by three facets almost identical in shape to the table. This particularity, quite rare in gemstone designs, is what has given it its name.

This design is very simple in spite of its complex appearance. Its three fold symmetry, its small amount of facets (55) and the location of the meetpoints make it very easy and pleasant to cut. It is intended for beginners who have mastered all the inherent difficulties of a standard round brilliant.

This design applies particularly well on medium and dark colored stones. Its total height (H/W = 0.625) is relatively small. Thus, the light passes through the stone easily. It looks very well on big stones (over 12mm) making the cutting process even easier.

The superposition of the crown's triangles and the pavilion's stars gives to this design a nice reflection, scintillation and luminosity. The COS and ISO brightness returned by GemRay at zero tilt for quartz is 70.3 % and 83.2 % respectively.

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