I don't think it's any color that is currently listed on Privett's site. They may be breeding other colors in small numbers, and putting them in assortments but not listing them separately.
Looking at your chick photos, and the illustrations in the thread you linked, I would consider these varieties most likely:
Blue Silver Duckwing
Fawn Silver Duckwing
Silver Ginger
Blue Silver Mille Fleur (if that exists-- it's not listed, but logically it would be Blue Mille Fleur plus the silver gene.)
The chicks illustrated in that thread don't have wing feathers yet.
Many varieties of chicks get dark feathers in their wings, sometimes with various multi-colored patterns, even if that will not be visible in the adult coloring. Many colors of adult chickens also have dark flight feathers that are not visible when the wing is folded.