The influence of different trace elements added on the color of gem-grade large single crystal diamond was studied under a certain pressure and temperature gradient with FeCo40 alloy as catalyst and high-purity graphite as carbon source. The results show that with the increase of Ti doping, the color of large cultured diamond changes from dark yellow to light yellow and then colorless. At the same time, with the doping of trace element B, the color of crystal changes from colorless to light blue, then dark blue.