Thanks for the info .From the VCA website....based on this I think malachite requires loving care!
Maintaining your malachite:
As this stone is especially soft and thus fragile, Van Cleef & Arpels recommends protecting it from scratches and sharp blows.
Please avoid washing malachite in water, as this will remove its protective polish and alter its brilliance
http://www.vancleefarpels.com/us/en/article/3178/Malachite?page=1&grid=9
I might ask VCA if they will offer a cleaning service for vintage alhambra Malachite because all jewellery needs cleaning from time to time .
But regardless I may throw caution to the wind and buy the magic long pendant as you can at least take the pendant off the chain to clean it.
I would love the long Magic pendant in white gold ,the thought of onyx or carnelian makes me