In all seasons, the plumage of the Ruddy Turnstone is dominated by a harlequin-like pattern of black and white.
Breeding birds have reddish-brown upper parts with black markings.
Non-breeding adults are duller than breeding birds and have dark grey-brown upperparts with black mottling and a dark head with little white. 
Juvenile birds have a pale brown head and pale fringes to the upperpart feathers creating a scaly impression.

1st & 2nd photo: In non-breeding plumage (winter). IJmuiden Pier, The Netherlands, 17 November 2009
3rd photo: In breeding plumage. Petten, The Netherlands, 14 August 2009
4th photo: In non-breeding plumage (winter). Brouwersdam, The Netherlands, 12 January 2021
5th photo: In non-breeding plumage (winter). Lauwersmeer NP, Port of Lauwersoog, The Netherlands, 16 April 2021