Orostachys boehmeri

Chroma, these are lovely photos. This is the first time I have seen the particular Orostachys.
How hardy are they?

They are very hardy. I live in about zone 6 and they survive without any protection.
In winter they loose their roots and make little balls. They look very dead, but than reappear again in the spring.

They are sure lovely to look at. I will have to try finding that one here in the U.S.

I don't think that would be a problem.
I saw this species in many mail ordering nurseries in US.
one of them:
http://www.glasshouseworks.com/perr-mo.html

Thank you Narcoleptic for the link. I Bookmarked it and will order in the spring.