from a private collection in Liguria

Typically sourced from Namibia (Erongo, famous for its intense blue-violet hues), China (Hunan, Yaogangxian), and England (Weardale), it is colored by color centers resulting from reticular defects induced by natural radiation, sometimes in combination with traces of rare earth elements (yttrium) or europium. It forms through low- to medium-temperature hydrothermal precipitation in veins associated with granites and metamorphic rocks, often alongside quartz, barite, and metal sulfides. It typically crystallizes into well-formed cubes or octahedra, with visible color zoning. Hardness 4 on the Mohs scale, density 3.18 g/cm³, perfect octahedral cleavage, often fluorescent under UV light (a phenomenon from which the name “fluorescence” derives).

A stone highly sought after by collectors for the intensity and purity of its blue color, which ranks among the rarest and most prized shades of the species; occasionally used in jewelry and decorative items (beads, points); a minor industrial mineral used as a flux in metallurgy and as a source of fluorine.