> "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.


Sorry - I think you've misunderstood me here, probably because I didn't
make
myself very clear to start with :)

What I mean to say was:  Open Pov, create a new file, use the menu item
Insert >> Scene templates >> Photons scene.  First render it straight
away.
Then change the ior of the glass to 2.47 (or whatever diamond really is)
and
re-render.  You'll see that the bright spots on the ground are no longer
bright.  This could be the problem with your diamonds.  Have you tried
setting the ior to 1.5 or so, just to see what a glass "fake" would look
like?

Thanks for the heads-up on gemcad - sounds useful.  Very useful in fact!

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