Tm, Er, and Yb codoped calcium-aluminoborate glasses were prepared. Intense visible luminescence was observed under excitation at a 325-nm wavelength. It was demonstrated that violet and blue luminescences (392, 454 and 478 nm) were mainly contributed by Tm, and green (514, 528 and 559 nm) and red (652 nm) luminescences were mainly contributed by Er. Energy transfer processes among Tm, Er, and Yb were evidenced, in which various colors of the luminescence could be easily tuned by adjusting the concentration and the kind of the rare earth ions in glasses.