Fire is the rainbow effect of how many colors the eye sees, how bright they are (intensity), the angular spread of the colored light (dispersion), reflection size and direction.

Figures A and C to the right are examples of how fire spreads out as it gets further away from the diamond. Figure B shows an example of how a fire reflection appears to your eye at a typical viewing distance. The circle shown is the typical size of your pupil. Clearly you can see only part of the fire reflection at one time. The diamond must be rocked gently to see all the colors in the reflection. Further proof of why a face up analysis only is not sufficient.
	Figure A	Figure B	Figure C