O-Pace
by Tom Herbst
| I designed O-Pace during April 2003, inspired by a piece of Contra-Luz opal and the colours of protest flags over here in "old" Europe. |  |
Feel free to change (or omit) the frosted facets to suit your particular viewpoint - we should all leave politics at the shop door.
The design is a simple brilliant type that windows intentionally to allow a better play of colour against a dark background. I used GemCAD and BOG to try to maximize the number and effectiveness of the light rays passing through the fiery regions.
In normal lighting, there is a subtle play of colour in the gem (top image), but when things are just right, the stone lights up with fire (bottom image).
It became clear that I would need to mount O-Pace with a dark background for maximum effect. I ground a thin disk of North Carolina black tourmaline (schorl) and epoxied it to the back of a standard Tripps-type mounting containing the gem. All in all, it worked very well (see pictures below).
Several days after cutting, a couple of cloudy regions began to form in the opal. The dealer claimed that it had been dry for many months, and I waited an additional 4 months before starting on it. Six hours in water restored the original clarity, but it looks like this one will have to be stored in water.
O-Pace is a straightforward design suitable for all skill levels.Cut the frosted facets on a stationary lap, since they come in very quickly!
At right is a 13 mm 4.7 carat O-Pace cut in Mexican Contra-Luz Opal.
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