Fisheye is a
reflection of the girdle on the pavilion facets visible in
the face-up examination of a diamond with a very small pavilion
angle.
It is one of the optical
effects like Kozibe, Nail Head and etc.
Figure 1.
The photo real and draft Illustrations show the stone with
Tolkowsky proportions and the stone with fisheye effect. Illustrations
obtained with DiamCalc software.
| a) Tolkowsky proportions (pavilion angle
is 40,75 degree). |
 |
 |
| b) Pavilion is too smaller than Tolkowsky
proportions (pavilion angle is 35,00 degree). Fish eye
effect. |
 |
 |
Figure 2.
The ray-tracing illustrate a fisheye effect as a reflection
of the girdle on the pavilion facets visible in the face-up
examination of a diamond. Pavilion angle is 35,00 degree.
Obtained with DiamCalc software.
|
