Richard Riss and Jean Louis Delaunay have confirmed the authenticity of this painting.
Privately owned since around 1957 and exhibited at the major Delaunay exhibition at the Städtisches Kunsthaus in Bielefeld in 1958, Rythme coloré, no. 618, demonstrates Delaunay striving to convey the impression of simultaneous movement and conjure up rhythm through the manipulation of colouristic effects. Inspired by the principals of colour first put forth by Eugène Chevreul in his 1839 treatise De la loi du contraste simultané des couleurs et de l'assortiment des object coloré, Delaunay can be seen here to use powerful, luminous colour to achieve immediacy and spontaneity. The brush is loaded and the first form confidently delineated with strong colour. Delaunay often began by defining a single, powerfully coloured centre circle or as in the present work, a semi-circle. The curved blade-like forms, juxtaposed against the cold and warm colours of the angular shapes around them, together achieve a sense of depth and intensity.