免费在线视频The reddish tone of the gold comes from copper. This fine gold is soft and corrosion-resistant and produces a precious metal that is high-grade, exquisite and highly popular in watchmaking. The colour nuances, depending on the copper content, range from soft rose to powerful dark red. At Lange, pink gold is used with 205 parts copper to 45 parts silver. This makes for a purity of 18 carats (750 ppt).