Differs from most other mediterranean species by the presence of two smooth spirals, rather close to each other, on the periphery of the last whorl, instead of only one, somewhat broader spiral. Two spirals also occur in C. diadema Monterosato, 1874, which is much more slender, with much smaller and more numerous protoconch whorls. The relatively bulky protoconch of C. tiara shows a number of curved axial ribs but no spiral sculpture.