Brilliance also goes by the name of "internal luster".
Observing brilliance is easiest in direct light, with the gemstone held at an oblique angle to the light source.
Observe the gem through the table while rocking the gem slightly.
You should see minute
areas
of
light that
seem to
"turn on and off" as the gem articulates.Caution: Don't allow surface luster or reflections to detract your eye.
While watching the flashes of brilliance, consider the following.
- The true color/hue of the gem can be observed in the patches of light.
- Saturation and tone are best determined by the patches of light.
- If the flashes of brilliance are not apparent, the gem is:
- Not Transparent
- Excessively included
- Poorly proportioned
- The greater the percentage of brilliance, the better is the quality of gem related to finish, transparency, proportion and clarity