The bi-gradient bug is really weird.  I found it when I was doing all the Enterprise renders over the holiday.

All the flat surfaces on the bottom of the models come out black but if you dial the horizon back one degree, it all gets fixed.

I haven't tried to re-produce it in the latest code version (151) but it was occuring in the previous two versions I was running (it was fine in the first few versions of C8 but it got busted along the way somehow).

I concur that moving the objects into a fresh C8 file should fix my gemstone issue.  I'll give that a spin.

-Kix