Playing with the "Supertoroid" primitive, ripped apart and heavily modified. The material I made here cost me a five and a half hour render time, but I think it was worth it in the end. This is sort of the equivalent of a glossy material with a roughness of around .06 in Cycles. One sun, 20 samples/12 softness. Environment lighting(white), power of 1, Falloff of 10/1/16 samples. 1920 X 1200
I used a sun, with sunsky enabled, power of 1.2, yellowish color, samples = 16, softness = 20, turbidity of 2, ambient occlusion/Add = .3, Falloff = 1, Samples = 12. Also experimented with Catmull-Rom AA here, seems to be crisp without many jaggies
Made with Blender 2.64, and lovingly rendered with Blender Internal
1920 X 1080
For those who are curious, I used a very flat black finish here with Diffuse Intensity at 1, and .20 on the Specularity with 20 for Hardness. I used two point lights, one close to the object, and one further away from it. Light specs are 12 samples for the shadows, and 10 samples for the softness. Energy of 1.2, and the lights were strategically placed so the flower would blend into the darkness. Background sky is totally black, and I didn't use any Ambient Occlusion or any other atmospheric lighting. The object itself is subdivided at a level of three, which made it a rather heavy mesh, but turned out nice and smooth. Blender Internal render of course.
EDIT: Updated with my original design. Same settings as above for the green.