Thanks for comments.
I experimented a bit with the cymbal material and came up with this:
Hope this is better.
atti: I’m not sure if this was the issue, but I flattened the rim a bit. Here’s a cross-section of the china cymbal model:
I’ve got rather poor knowledge about drums (I roughly know how the drum kit look alike and who was Buddy Rich). If there are more mistakes resulting from my ignorance – point them out.
By the way, I came across such a problem:
The hard shadow appears when tangent shading is turned on. There are no sharp edges or double vertices here. Am I doing something wrong or is this a common problem?