Medium-sized to large, moderately solid to heavy. Last whorl conical to slightly ventricosely conical, outline convex at adapical fourth to third and straight below. Shoulder angulate to subangulate or almost rounded, usually with a fine carina. Spire low, outline concave to slightly convex or sigmoid. About first 5 postnuclear whorls weakly tuberculate. Teleoconch sutural ramps flat to slightly sigmoid, with 3-4 spiral grooves, changing to many striae in late whorls. Last whorl with obsolete spiral ribs at base. Height: 48-100 mm. Colour bluish violet or white shaded with violet or cream. Last whorl usually with a paler spiral band at centre; in shells from India and Oman, a weak to prominent, variably broad, violet to orange spiral band on each side of centre. Larval whorls white. Teleoconch spire tinged or radially streaked with pinkish orange or pinkish violet. Aperture white, pale violet or pale orange. Periostracum dark red brown and opaque (specimens from Natal), light brown and thin (Coomans & Moolenbeek, 1982). Animal reddish brown (Veillard, 1972). Radular teeth long and slender, with 2 opposite adapical barbs; long serration from end of anterior barb 2/3 the length down the shaft; basal spur absent (Rolan, pers. comm., 1992).

C. berdulinus is most similar to C. kintoki and also resembles C. coelinae and C. martensi. The latter species differs in its more angulate shoulder, more prominent spiral sculpture on the late sutural ramps, non-tuberculate postnuclear whorls, and yellow to orange colour.

Range: Natal (South-Africa) to Mascarenes, Somalia, S. Oman and S. India. Type Locality: "off the coast of Reunion, near the port of Pointe des Galets." Habitat and Habits: In 40-140 m; holotype reported from muddy sand bottom.