Possibly dried out finger tips for me, but that's about it.
Possibly it's the magnesia in the Choseras that doesn't like your skin?
That's the main difference of Choseras to anything else, and as far as I'm aware most of the stuff in man made stones is pretty much inert, biologically speaking. Just abrasive and a binder, and the abrasive shouldn't cause much problem. A quick google says that magnesia is actually a good thing for skin problems a lot of the time...
Most likely the residue being hygroscopic and sucking the moisture from your skin. Wash hands properly with soap and if possible warn/hot water after using the stones and maybe a good skin cream if needed?
(I'm not one to use skin cream, but the pretty young lady who lives here does...)
Good luck, and if you find out anything specific do please let us all know.
I haven't noticed anything particularly bad with Choseras either. Like Schtoo mentioned, my fingers can get dry if I'm constantly wetting and drying them for a few days. If I'm working on regrinding tips, for example, I will where away the skin on the tips of my fingers, too but that's obviously not what you're talking about.
I think Schtoo is right and it's all about skin dessication. I had been busy a whole night and wiped only my finger tips. The fingers' back were covered with residue for hours.
I'm very happy after a little amateur 'provocation test' I could exclude a contact allergy.
Your contributions have been most helpful, thank you very much. Bernard