Please help...I am clueless. My wife found this broach on Ebay and the seller is local. We looked at it last night under a loupe and the diamonds are very cool european cut and the turquoise is about 2 inches long. The problem is I do not have any idea how much something like this should be? I do not want to overpay and the seller has a make offer button. PLEASE PLEASE HELP! The gold is 14k but she said it might be 18k. It looks 18K.