We demonstrate a highly efficient, tunable, ∼5 GHz linewidth diamond Raman laser operating at 479 nm. The diamond laser was pumped by a wavelength-tunable intracavity frequency-doubled titanium sapphire (Ti:Sapphire) laser operating at around 450 nm, at a repetition rate of 10 kHz with a pulse duration of 50 ns. The Raman resonator produced a continuously tunable output with high stability, high conversion efficiency (28%), and beam quality (M2<1.2). We also demonstrate that the linewidth and tunability of the pump laser is directly transferred to the Stokes output. Our results show that diamond Raman lasers offer great potential for spectroscopic applications, such as resonance laser ionization, in an all-solid-state platform.