Mother of the bride dress

My mom bought this from a website called PromLily. There’s no tags on it but it’s a size 10. New and never worn. Color is lavender Reformation, House of CB, Revolve, Anthropologie, Free People, Wilfred, Babaton, Agolde, TNA, Sunday Best, Citizens of Humanity, Levi’s, ALO, Lululemon, Amanda Uprichard, For Love & Lemons, LF, Golden Goose, Lovers+Friends, Zimmermann, Brandy Melville, Zara, Madewell, Aritzia, Top Shop, H&M, Max Mara, J Crew, Banana Republic, rag + bone, rag and bone, BCBG, Urban Outfitters, All Saints, Alice and Olivia, Pretty Little Thing, nastygal, shein, dolls kill, BP, old navy, American apparel, forever 21, lands end, everlane, bonobos, ASOS