Hi, I am English and ‘you have beautiful skin’ is correct. You would say ‘you have a beautiful nose,’ ‘ or a beautiful face’ , but not ‘a beautiful skin’ .
As I was told, "a beautiful skin" works in some contexts. Especially that potentially it could be "deer skin" or something like that.
Lack of article is the main version, though.
The English sentence doesn't sound good to me, I would say you have a beautiful skin