Prom dress

I wore this dress twice. Once for prom and the other for a formal event. It’s a very sparkly dress and for the color some people have said it looks gray, purple, and blue so I really don’t know what it actually is. To me it’s a mix of blue and gray. Please note that this dress is altered to my height with heels. With heels I was like 5’6 or 5’7 in this dress! The straps also cross in the back!! I’m willing to negotiate I want to get rid of this!!