looks like even though I set the samples for 16 and ray bounces for 16 they defaulted back to 32 when I started to render, must have reopened the file and didn't notice. I changed the settings to 4 samples and 32 ray bounces and the diamonds rendered in about 16 minutes. I can tell very little difference in the renderings but there is some difference. I guess I will just have to live with the shading in Alibre and look to export to blender or something else for rendering.
Need to find out where I can download the new Keyshot I keep getting 1.9 not 2.0.
Need to find out where I can download the new Keyshot I keep getting 1.9 not 2.0.