It’s difficult, but not totally impossible to determine the sex of a Silkie. There are signs that can help you long before the first egg or crow of a rooster. Behavior and size can be a good indication of sex.
Roosters are often more bold, have that sturdy or stronger look, and sometimes they are larger. These are noticeable traits, even when chicks are still in the brooder. Look for brighter, or sharper distinction of color in birds of the same when they reach 8 or 9 weeks. Rooster seem to stand out more, dazzling you with a little wow factor.
These Silkies are all just under 3 months old, 2 white, 2 buff. The white Silkie pictured below is probably a Rooster. He is much larger, and has been at the top of the pecking order since the second week of life. The size between pic 1 and 2 is obvious, recognizing behavior traits is something you’ll notice by watching your own birds.
All we really can do is learn behavior traits of roosters and recognize indications such as size. But I must admit, I’ve been absolutely positive on having a Silkie rooster… and been surprised 6 months later when it laid an egg. Gotta love those Silkie Bantams!
FYI: Most, if not all hatcheries sell only straight-run (unsexed) Silkie Bantams except My Pet Chicken. They offer sexed female Silkie chicks at a higher price. They also will ship only a few. They did a good job sexing five female Silkies for me, 4 out of 5 were indeed females.