Formation of ohmic contacts on boron-doped diamond using zirconium and niobium has been studied in comparison to the commonly used titanium or tantalum contacts. Metal contacts were fabricated using standard micro-fabrication technologies on epitaxial layers with different boron concentrations. Room temperature specific contact resistance was determined using the circular Transmission Line Model after annealing at various temperatures. The specific contact resistance varies considerably with boron concentration and annealing temperature. Zirconium and niobium form ohmic contacts on highly boron-doped diamond after high-temperature annealing with a specific contact resistance comparable to that of titanium and tantalum contacts. Furthermore, we observed zirconium contacts showed better thermal stability upon high-temperature annealing compared to titanium and other metal contacts. These results emphasize the potential of zirconium for the formation of ohmic contacts on boron-doped diamond.