Cartier Juste un Clou ring, 18K pink gold, B4092500. Cartier Juste un Clou ring, 18K yellow gold, B4092600. Factory Reference: 1000257 Metal: Available in 18k white gold, 18k yellow gold and 18k pink gold. Gold weight: 7 grams to 7.8 grams depending on the ring size. A nail becomes jewelry. Designed in 1970s New York, the first Juste un Clou …