Male ring-necked ducks are predominantly black with gray sides and a white crescent in front of their wings, while females are a mottled brown with a white eye ring and a white patch near the base of their bill. Both males and females share a distinctive gray bill with a black tip and a white band.

Male:
• Plumage: Mostly black with gray flanks and a white crescent-shaped mark in front of the wing.
• Head: May appear iridescent purple.
• Bill: Gray with a white ring and a black tip.
• Neck: A faint cinnamon-colored neck ring is usually not visible.

Female:
• Plumage: Mottled brown with a darker back and a paler face.
• Eye Ring: A prominent white eye ring.
• Bill: Gray with a white band near the tip.
• Face: A white area near the base of the bill.

Similarities:
• Both sexes have a gray bill with a white band and a black tip.
• They are diving ducks with a peaked head and a sloping forehead.
• They have yellow eyes.