Blue pavilion mains and Black ones in ASET

[treasurehunter]

Blue is for contrast and Black is light loss am I correct ? Often in the 42.5 % pavilion deep stones I see a good looking ASET but then there are some mains that are Black and not blue is this a big cause for concern ?

 

[Karl_K]

The stone that goes with that image does not have a 42.5 degree pavilion.
Green center its under ~40.75

 

[Karl_K]

Woops just saw you said 42.5 % not degrees.

Simple the virtual facets are drawing light from the camera/lens hole in the ASET scope in the center of the blue zone.
Some people enlarge the hole to improve photo quality which makes it show up even more.
Such a stone might have obstruction issues on the hand but would make a wonderful earring or pendant stone.