One of my favorite projects during an almost ten-year long relationship with Findomestic BNP Paribas Bank. A set of rather special VISA credit cards (green for personal and silver for business) inspired both by the BNP corporate color (emerald green) and the emerald as a symbol of wisdom, growth and patience. No, really, it’s true. I’ve read it on Wikipedia.
A bit of trivia - it is so prized, that carat for carat, a fine emerald may be two to three times as valuable as a diamond.
Second bit of trivia - based solely on this design change, demand for those credit cards was increased by about 37%. So, it seems that design matters, after all.