Crested Echeverias look so beautiful. What makes them crest?

Magic?

Presumably whatever it is, it tends to be easily reversible (2 normal branches circled):



This crest ended up mostly reverted and did not survive long term.

Why do you think it did not survive? I've seen crested plants for sale and some in the landscapes around here that seem to have been around for years. Such a lovely crest, too bad.

It was a gift from mother nature to start with, so I did not mourn the loss. Easy come, easy go.

I think some crests are much more stable than others. The more spontaneous they are, the more likely they seem to be to revert. A crested plant that has been propagated as a crested plant for many years is more likely to stay that way. Something similar goes on with variegation.... a spontaneous variegate is more likely to revert (sort of by definition) than a long-term stable variegate.

Here's a reversion that has been working in my favor, generating lots of new (normal) heads for propagation:



Curiously the crested plant has given me many more new (normal) heads to root than the normal one I have that's a few times its size. This crest is still definitely teetering on the brink.