Making diamond

[Scrambler]

Hello.

I'm trying to make a diamond, but getting very weird result - the diamond accumulates too much shadows even if it's overexposed with light (see the first attached picture (http://www.newtek.com/forums/attachment.php?attachmentid=51351&stc=1&d=1192969011)).

Trying to get result at least as nice as in LW web help (see the second attached picture (http://www.newtek.com/forums/attachment.php?attachmentid=51352&stc=1&d=1192968965)) but have no luck.

My diamond consists of two surfaces - the diamond itself and the air (the same as diamond, but polygons are faced inside the shape and refraction index is 1.0003) both are 100 transparent (see attached zip-file (http://www.newtek.com/forums/attachment.php?attachmentid=51353&stc=1&d=1192969042)).
Color highlight and Color Filter are used to add some flesh to diamond.

I tried to play with different attributes, but my diamond is always dark at sides and doesn't "multiply" absorbed light.

Any suggestions of "where to dig" to get more realistic result?

[warrenwc]

Now that we have Volume stacking, you don't need air polys- but some of us prefer the look of putting dielectric on both sides of the surface for more internal reflections.

[Scrambler]

Now that we have Volume stacking, you don't need air polys- but some of us prefer the look of putting dielectric on both sides of the surface for more internal reflections.
Thanks for the idea!
In fact I used Delta node to make diamond - with Dielectric node the diamond looks "dead" like cheap glass-fake.
Delta makes diamond vivid and shining, there even some sparks occurred at vertices and edges :) (I guess they are results of rendering errors or incorrect scene lightning).

The next aim - is to obtain real (not pre-calculated or pre-drawn) dispersion.

[JeffrySG]

Not sure if you have it or not but the Index of Refraction for Diamond is:
2.417

[Scrambler]

Not sure if you have it or not but the Index of Refraction for Diamond is:
2.417
Thanks, I'm aware of this.