Aqua hued "open-back" marquis have a large ab chaton in the center with swirls of ab chatons forming three loops on one side.  The brooch measures 2" by 2 1/4".  Set in a silver plated metal.  Pin clasp is secure.  The camera seems to show a mark on the back metal above the pin clasp, however, there is nothing there.  It is all silver plating.  Great vintage condition.  Thanks for looking and please email me with any questions.