For the cosmetic field, omniphobic cosmetic pigments under the form of a core shell structure: the core is or includes of a metal oxide on which is adsorbed poly(β-(1→4)-D-glucosamine) chains; the chains being acetylated, or partially or totally deacetylated. Also, the process for manufacturing the omniphobic cosmetic pigments, including: (i) preparing an acidic aqueous solution including metal oxide particles and a poly (β-(1→4)-D-glucosamine), the poly (β-(1→4)-D-glucosamine) being acetylated, or partially or totally deacetylated; and (ii) increasing the pH until 12, of the solution obtained at step (i) in order to obtain the adsorption of said poly (β-(1→4)-D-glucosamine on the metal oxide particles and the precipitation of the resulting metal oxide particles coated with the poly (β-(1→4)-D-glucosamine.