Thank you David - I think I have mistakenly used the word 'patina' here, in an inappropriate way. I didn't mean to imply it was due to significant age of the piece, I just wanted to refer to the darker areas under the chin, for instance. Would 'shade' or maybe 'glow' or something else be more correct?
English is not my native tongue, so I guess I'm sometimes prone to accidentally use words, unaware of their correct or full meanings. Sorry for the confusion!
Personally, I have a sweet spot for darker more "glowing" ivory. Either due to years of handling or tea-dying, it doesn't matter so much to me. Maybe it's because I see so much of the pearly white, modern touristy stuff at my work.
I feel the same way about bone. Btw. if anybody has a reference to a description of tea-dying of these materials, I'd love to read about it?
All the best, - Thor