Thank you i kinda of thought so but wasnt sure i got them off ebay as hatching eggs and was told they were a rare variety of Dorking. I was told they were Birchen.he's not any recognized variety... silver grey has much more silver/white, less grey. colored would be marked similarly, but have straw hackles and red shoulders...
they're also supposed to have single comb, not rose.
sorry to say, i honestly don't think you'll get more than meat prices for them. good luck tho.