The dress appears to be a satin or charmeuse-style evening gown in a vivid royal blue color. Key details include:
Silhouette: Fitted column/sheath style that skims the body down to the floor.
Neckline: Deep sweetheart neckline with structured cups.
Straps: Thin spaghetti straps.
Fabric: Shiny satin-like material with a smooth reflective finish.
Bodice: Corset-inspired seaming/paneling that gives structure and shape.
Waist/Hip Detail: Soft ruching/draping across one side of the hips for a flattering effect.
Slit: High front slit on one leg.
Length: Full-length/maxi formal gown.
Style vibe: Glamorous, prom-ready, red-carpet, or formal evening wear.