Unlike traditional porcelain or oil painting, Blanca insisted on using materials salvaged or inspired by the sea. Many surviving pieces are composed of tinted with actual crushed madrepora coral and oxidized silver leaf, creating a unique "saltwater patina" that turns a pale greenish-white over time. If a piece claims to be authentic Sirena work but lacks this specific, slightly rough texture, it is likely a reproduction.
The name "Blanca Sirena" (Spanish for "White Mermaid") also appears as a recurring motif and symbolic figure in various literary and artistic contexts: Poetic Imagery: duchess blanca sirena work