"Andrew" <ast### [at] hotmailcom> wrote in message
news:3e722e53$1@news.povray.org...
> You're using the correct IOR for diamond, right?  I don't have
access to
> any real diamonds to test this (oddly enough), but I don't think
they
> show much in the way of caustics.  A quick test with pov seems to
> confirm this - try rendering the example scene straight from the
Insert
> menu, then try it again with an IOR of 2.47.  The bright spots on
the
> ground certainly don't look so neat.

    Hiya Andy, are you seeing something different to me then? The only
bright spots I see are the reflections from the table surface. I'm
using most of Jurgen Sharfys' code and his IOR is 2.41.

    I'll give 2.47 a try.

  My caustics are low at the moment, I'm using .3 - I tried higher but
I thought the stones looked TOO colourful.

>
> Also, (I might just be making this up here) I think that the diamond
> cuts are designed to reflect light back out towards the "user" :)
In
> other words, all the sparkle comes straight back at you when you
look at
> them set in a ring, hence their sparkly appeal.

      You might be right with this image. I turned reflection off.

      Should I try turning refraction off and reflection on then? What
do you think? This image took around 1.5 hours at 640x480 aa 0.3, and
then I cut it a little.



>
> On a seperate note, where did you get the geometry?  And are they
meshes
> or CSG?  I've only ever found CSG versions of povray diamonds, and I
> didn't have much luck turning up a geometrical description of a cut
> detailed enough to make a mesh from when I searched.

   'Ere guvnor... wanna know a secret?  ;)  They're meshes. Have you
got a prog that can convert .dxf files to .pov? I used freeby Rhino.
Go here: www.gemcad.com (free 30 day trial), save as a .dxf, and then
open (whatever prog), and convert to a.pov file. The great thing with
gemcad is that you can alter the amount of facets you might want with
a click (I don't work for them!) - although I haven't tried this in
this image.

Have a play, it's fun. Looking forward to seeing something better than
mine (which won't be difficult!!)

      ;)

   ~Steve~



>
>

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