You know, I got really lucky when I bought those sebbies. Last spring, I tried to hatch some out. I don't know how much money I spent, BUT I just couldn't hatch any...
This past fall, I was in Maryland, to buy some peafowl chicks, and the woman had a flock of Sebastopal geese! I knew, I just had to have a pair. She gave me a great deal on a pair of unrelated young birds. The gander is 2 years old and the goose is about 8 months. Sebbies are sex link. Female's have dark patterning on their feathers when they are born. My girl still has some dark feathers, but they are fading.
Lisa
He's an Easter Egger (Ameracauna mix). He does have beautiful Columbian-type feather coloration.
Addendum: If he had the Silver coloration, he would look similiar to the Silver Duckwing OEGB roo that's my avatar. I had a Silver Ameracauna purebred bantam roo that had almost the same color pattern, except the head and neck were streaked with black.