Are they chocolate or are they golden? It's hard to tell from your pictures because in the one picture they look like a gold yorkie puppy. Chocolate is darker and their noses will turn chocolate as well. Whereas goldens can be light gold or dark gold and their noses will turn black. The dark gold usually has black intermingling hair mixed in when young usually on the tail, ears, etc. Chocolate is very obviously a chocolate color all over except with tan points like the feet and chest.
There are no health issues in chocolates, goldens or partis, it is just a recessive gene that both parents have to have.
I myself have a chocolate yorkie. He is 3 years old and just a little sweetie.
Here are gold yorkie pups...
Here is a chocolate yorkie pup with a standard one. The chocolate was my baby when he was first born 3 years ago.
These aren't very good pictures to show you the difference, you can probably do a search on here and find better pics but it gives you an idea.