Skip to end of metadata
Go to start of metadata

Although creating a diamond or any gemstone is very simple in Arion Render once you know the Index of Refraction, the dispersion value and the attenuation color,
there are a few things that are worth mentioning in a tutorial.

 

Start with a standard Arion BSDF material.
The preview sphere used in our tutorials has been unsmoothed for the purpose of showing diamond-like reflections and refractions.

BRDF attributes
Fresnel IOR 1.51 0.0
Falloff 46.5 16
Color
Edgetint
Roughness | % 100
Bump | % 10

 

Then set the correct Fresnel IOR for a diamond (2.417 for example) and lower the Roughness parameter to 0, diamonds are shiny, very shiny.

BRDF attributes
Fresnel IOR 2.417 0.0
Falloff 46.5 16
Color
Edgetint
Roughness | % 0
Bump | % 10

 

And enable Transmittance.
Here we already have a problem, dark faces are visible. This is due to a too low Refraction bounces depth for a material like a diamond.

Transmittance
Enable
1-sided
Abbe 63.5
Atten. | cm 25
Color

 

Rendez-vous in the render settings parameters, under the Global Illumination rollout to adjust the Refraction depth to for example, 100 (it usually doesn't make a visible difference to use higher values).

Global ILlumination
Spec./diff | % 5.0 95.0
Specular 8
Glossy 8
Diffuse 8
Refraction 100
SSS 8

 

Then back to our material settings, enable dispersion by checking on the Abbe parameters and set its value to 50 or 55 which is a good value for diamonds.

Icon

Due to the high Refraction depth and the fact that diamonds really uses it all, rendertime can become significantly higher than without dispersion.

Transmittance
Enable
1-sided
Abbe 50
Atten. | cm 25
Color

 

From there the only thing left is to adjust the Color and Edgetint gray values to control the reflection if you find it too reflective, and add a very slight amount of attenuation optionally.

Below is a comparison of the diamond material we just created from scratch, compared to a material using a complex IoR file that does it all for you.

Custom materialComplex IoR

 

The complex IoR version is naturally better, as it takes into consideration all the different wavelength of light with varying IoR and Abbe values for each, but it's pretty close.

 

  • No labels