ONE string of pearls is a great idea! Classical, as is the dress.
I like the idea of the gloves..... as to their colour, normally, I'd say black goes with anything, but the colour of your dress, being brown-ish (sorry if the colour hasn't reproduced properly on the Internet), is the exception that proves the rule. I'm not sure about white.
I think for the gloves your best bet is to try and find a pair to match the dress, or failing that, dye them to match.