Radiant cut diamond versus crushed-ice diamond.

[Chelsea Palmer]

I doubt that radiant has a bow tie.
I expect that dark zone will flash bright with the slightest movement.
A bow tie can remain dark for up to 20 degrees of left right (E-W) rotation.
If the dark flashes on off it is exactly the same as the 4 bow ties in a well cut round brilliant.

Such a beautiful diamond. Thank you, Garry H.