This item is a vintage rhinestone brooch featuring a large, smooth blue glass cabochon center stone, surrounded by iridescent aurora borealis (AB) and blue marquise (navette) rhinestones. The brooch has a radiating or starburst design, sometimes referred to as a floral or abstract cluster style. It incorporates various cuts of blue rhinestones, including a prominent central "moonstone" style cabochon and pointed marquise or "navette" cut rhinestones around the edge. The smaller, round accent stones have an iridescent finish, which causes them to pick up different colors in the light. This style is characteristic of mid-20th-century costume jewelry, typically dating from the 1950s or 1960s. Similar unsigned pieces are often attributed to prominent costume jewelry makers of the era, such as Juliana (D&E), Weiss, or Trifari.