Two objects (gemstone and plane), one light (sun), no background/world, and one material. 5000 samples.
Given the dark surfaces/reflections, I would say that the number of bounces is not sufficient. Are you rendering using settings similar to the Full Global Illumination preset?
It probably does need more bounces (a lot more), but the point was simply to get that random refraction and have it affect the caustics. It was never intended to be a high quality scene.
State that in the description next time… :yes:
As tests go, readers (at least me, for sure) like to know the story behind… what was your intention, goal? If there was any? Any reference image, concept, thesis…? Part of a bigger scene? Done using a shader, a lamp/light, script… on GPU, CPU? Tech, Specs, Stats… :rolleyes:
can you put cycles node setup here , once I did the same gem , rainbow colors was more realistic