What represents scintillation on IS image????

[Maxine]

I have an old diamond w/not great specs OR IS image, but it has pretty good scintillation....What part of IS image = scintillation????

 

[valeria101]

Garry is the one to answer this..

Just IMO, everything does - since that "scintillation" thing is supposed to be the glitter obtained from changing reflected light direction from one facet to the next. The IS just colors in different ways light reflected at different angles...
If anything, perhaps strong contrast helps scintillation after all - and that reads as black and white spots distributes all over the stone under the usual top-down IS image.

No idea if there is an official opinion about this.

 

[Garry H (Cut Nut)]

If you l the top row here http://www.ideal-scope.com/using_reference_chart.asp
the ordere from best to worst is from the top left: 2,1,3,3,4
The second row:
1,2,3,4,5.

We are looking for evenly dispersed contrast between red and black and to a lessor extent, between red and white.

So the top left stone has thinner dark stars then the second stone, which also has a little more strategically placed leakage.