I'm working on a large project and I need pearls. My Mom has lots of high-quality pearls, which means I've been around pearls a lot my whole life--nearly all the pearls I've seen in Poser look like plastic or at best ceramic beads. Fabi's look better than most, but still...I'm looking for accurate pearls with proper reflections, SSS, irridescence, etc. This is probably a task for Bagginsbill. :P

On a side note, I also need some gemstone cabachons. Would those be the same as glass but with different IOR?

bill may be otherwise occupied now, but the pearl shader in theory could be a variant of his candy-apple car paint shader with the three-layered reflective/colour/refractive fx.  pearls may also scatter light, which would probably not be seen in a metallic shader.  bill posted a script for generating a simplified version of the candy-apple shader in snarly's metals thread.

Thanks, Miss Nancy. That might work, plus it gives me a reason to finally learn how to use Matmatic. :)

I don't think irridescence can be done properly in poser yet.

I've faked it pretty well with a color ramp and a clouds node.

Can you post a picture of an object that has your shader?

Also, judging by wiki description, the multiple reflection might be doable if you know how to get the math right, which form of interference to use, etc.  But, if there are multiple causes of it as is hinted, you'd have a lot going on and you might need different shaders for different objects.

Well, I'm a little embarrassed...It seems that Bagginsbill has a pearl shader included with Matmatic. And a quick test render reveals it to be everything I could have hoped for.

On the faked irridescence, yes, I'll post a render and a material room screen capture of what I've done with that. It'll probably be tomorrow, though. 

like this ?

http://www.runtimedna.com/forum/showthread.php?63209-SSS-on-non-human-things&p=609251&viewfull=1#post609251

http://www.renderosity.com/mod/forumpro/showthread.php?message_id=2777761&ebot_calc_page#message_2777761

Quote - http://www.renderosity.com/mod/forumpro/showthread.php?message_id=2777761&ebot_calc_page#message_2777761

Thanks! That's more or less how I did it, except yours looks better. ^_^

On my second question, would a sapphire or ruby cabochon look more or less like glass but with a different IOR? 

Yes. Looking in posted IOR values on the Internet, both ruby and sapphire are reported to be 1.76. Glass is typically 1.54 to 1.65.

There is a danger in trusting Internet postings on IOR. I went looking for confirmation of car paint IOR values, and found a guy who blatantly plagiarized what I had said, which means he had no clue any more than I did. grin

If you want to see this amusing punk who literally stole my explanation of IOR, google this exact phrase:

"particular rate and degree that reflections increase with decreasing angle of incidence"

Google will return my car paint shader page,

https://sites.google.com/site/bagginsbill/free-stuff/car-paint

and this blog called bohemiantruckstop.

http://bohemiantruckstop.blogspot.com/2010_11_01_archive.html

I wrote:

PM:IOR - The "index of refraction" controls the particular rate and degree that reflections increase with decreasing angle of incidence. While there is no actual "refraction" happening in this shader, the concept of IOR is commonly used to specify the parameter needed control the Fresnel effect in a realistic way. (The glossy "clear coat" layer on top of car paint actually is refractive, and the index of refraction controls the reflectivity as well.) The IOR of water is 1.33. The IOR of glass is typically around 1.54. The default value of IOR in the car paint is 1.45. Decreasing the IOR will make the surface less shiny. Do not decrease it below 1. Increasing the IOR significantly past 2 will make the surface appear more metallic. Since the "clear coat" layer on car paint is not a metal, you shouldn't go much past 2 for realism. (In real life, certain extremely expensive paint jobs can get the IOR up to 2.)

He wrote:

IOR - The "index of refraction" controls the particular rate and degree that reflections increase with decreasing angle of incidence. The concept of IOR is commonly used to specify the parameter needed control the Fresnel effect in a realistic way. (The glossy "clear coat" layer on top of car paint actually is refractive, and the index of refraction controls the reflectivity as well.) The IOR of water is 1.33. The IOR of glass is typically around 1.54. The default value of IOR in car paint is 1.45. Decreasing the IOR will make the surface less shiny. Do not decrease it below 1. Increasing the IOR significantly past 2 will make the surface appear more metallic. Since the "clear coat" layer on car paint is not a metal, you shouldn't go much past 2 for realism. (In real life, certain extremely expensive paint jobs can get the IOR up to 2.)

The date of his blog post is November 7, 2010. The date of my page was last edited is July 13, 2010, but I wrote that description on June 8.

Notice how he had to edit to remove where I mention "this shader" - but that's all he did. Stupid punk. He even left my grammar errors.

bill, I couldn't get the pearl demo in your 2012 matmatic to render well.  can you show a render using it?  I may be doing something wrong;  need some tips on how to use it.  I saw that it uses scatter, unlike the 2006 iridescent example.

Thanks, Bagginsbill, that looks like exactly what I was looking for. :D

 @Miss Nancy: Did you have an environment for the pearls to reflect? I set up a basic render with BB's Environment Sphere and some of Synthetic's lights (so I didn't have to wait for IDL) and it looked absolutely perfect to me. 

zaarin, can you post your render of bill's 2012 pearl demo?  I can set it up as you say, but would like to see what it's supposed to look like first.  my render came out like the demo thumbnail - greyish-white.  it may be very dependent on directional light sources.

All right, it was saved. I set the sphere as invisible to camera, which is why the background is transparent. I forget which file I used on the sphere...it was HDR and it was interior and it was by Brian James. All I remember. The light set was "Realism" from Synthetic and Blackhearted's ProStudio--I highly recommend their sets, incidentally. The material was applied to a hi-res sphere scaled up for easy viewing. 

thanks for render, zaarin.  it looks nice!  similar to what I got, similar to a cultured or natural white pearl with no iridescence, which might be added using bill's 2006 method.  it would also be interesting to see an opalescent effect (not on a pearl, but on a stone surface).

I haven't had a chance to render it yet (or I did, but it was a big render and sadly crashed), but I did set it up according to Bagginsbill's methods (only using vary pale colors) and plugged it into both ks_microfacets--it looked good in the material room at any rate.

this is what I got for the matmatic demos. ISTR izzy said the scripts didn't work in OS X, but that may no longer be the case.

IMVHO the context of the pearl shader will be critical, e.g. may look better next to human skin.

That's probably true about context--and to some degree true in real life, as well. The carnelian looks spot on, though.

I really like the pearl shader and the others that come with PP2012, but I do wonder if we can use them in retail products if we alter them somewhat.