by Tom Herbst
I designed Topo to teach myself how to do checkers. The combination
of a classic brilliant-type pavilion with a checkered crown produces
a truly spectacular stone.
Topo is a simple and fast design, BOG optimized for ISO (94.5%) and
tilt in topaz. The table can be omitted for smaller stones.
The name is yet another literary tour de force. The original GemCAD
file was called TopO for "Topaz: Oval". Ahh, how deep run the wellsprings
At right is a 9x13 mm, 6.5 carat Topo cut in flawless topaz.
GemCAD and GemRay output for Topo appear below. The GemCAD file is available