What is the traditionally correct color for a bride to wear for her second marriage?

Any color is fine, including white which is a symbol of joy. You could also go for ivory, pastels, silvery gray, mauve, etc. Just do without the long train and veil, which are generally reserved for first time weddings. Flowers, a tiara, a hat, etc. or nothing at all will work best for second timers. The time of day and formality of the wedding can dictate the length of the dress, but really any length you prefer is also fine. Many second time brides go for dresses with beading or embroidery or a suit with long skirt and jacket instead of the lace and ruffles. Bottom line is wear whatever you are comfortable with.