Joan wore this gown in episode 73 of season 4 "Lancelot".
Alexis wears this gown in a scene while in her penthouse apartment before leaving for a party. Even though Alexis told Dex she would take her own car and meet him at the party, he arrives at her apartment by surprise. The two end up staying in her penthouse for a while in this steamy scene.
This gown is white fabric with vertical lines of chalk white bugle beads through out, with close equidistant spacing in between each row. The neckline and back have a low scoop and the wrists and neckline are trimmed with 6 rows of beads without spacing. The gown has a center slit with three pleats on either side which begin at the waist line.
This gown was originally sleeveless and came with a matching jacket. After it's appearance on Dynasty, the sleeves of the jacket were removed and added to the gown.