Ivory "rings" on chanter tops

[pjpjpj]

I’ve seen a few all-metal chanter tops (mostly Rowsome) which have ivory “rings” around them. Paddy Moloney had such rings on his Rowsome chanter in the 1960s and 1970, but by the early 1980s (notably the Chieftain’s tour of China) the rings were gone. I’m curious about how stable these rings are. Is the ivory prone to cracking? Like with wooden flutes which sometimes develop cracks at the tuning slide, does ivory expand/contract?