Alex Evenings gown Vintage? Size 20

Alex Evinings Gown. Maybe vintage. Size 20 $200.00 OBO. You pick up.. cash only. I know I've had it atlest 15 years. Time to let someone one else enjoy it. It is a slate blue/grey, maybe a little purple shade color. Dress is 54" in length. From top to hem. Was hard to get exat color in the photo...