Muscovies? When can I know?

[VQZ600]

I bought 9 ducklings yesterday that are supposed to be about 10 days old, per the CL ad. Some of them look like they could be muscovies, but two of them are all black. I have seen muscovies be mostly black as adults, but not likes these. At what age should I be able to tell if they are truly muscovies? Thanks!

 

[The Moonshiner]

Post good pics and someone will help you now.

 

[Gray Farms]

If they are 10 days old, and your familiar with Muscovys, some can tell now. Post pics.