If you at this standard round brilliant closely you will notice brighter flash than darker flash as you turn it. This because the tonal values, of two very similar colors, are different. This eye clean gemstone is bright and flashy and weighs 2.92 carats.
Face up this standard round brilliant appears to have a nice even medium dark forest green (green with a blue touch), but it is hiding the truth. When I turned it over to check for inclusions/flaws etc. and rotated it, I could clearly see its tone value change threw the c axis color and the a/b axis color. So after seeing that this beautiful gemstone is eye clean and with fine crystal, I looked at the gemstone face up again. As I slowly turned the stone, I realized, as I now expected, that some angles of rotation produce a brighter flash than others. There was my confirmation of the stone having been cut with its table parallel to the c axis. I usually can clearly see four slice of pie segments, face up, on stones that are cut that way, but in this case the different colors/tone values mix so seamlessly that a casual look misses the effect. This neat and mysterious gemstone weighs 2.92 carats.
Bruce
