Desmond Guilfoyle published an article on the "Montres Bijoux" series of Constellations of the early 1970's.

http://www.mediafire.com/view/f2wh1...ins_of_the_Sixties_and_Seventies_June2013.pdf

Your watch looks like a Ref. BC 353.0013, as shown on page 14 of the article. If so, it should be 18K white gold. You'll need a jeweler to confirm the metal content. Today's collectors love white gold.

However, collectors don't love the integrated bracelet styles from those days. Value is probably limited to gold melt plus a very small premium for the movement (if it working, of course).

Hope this helps,
gatorcpa