Diamond cutting tool

A diamond cutting tool comprising a base metal part and a diamond part joined to the base metal part,

• wherein the base metal part is made of an alloy containing tungsten carbide,
• the diamond part includes at least a cutting blade,
• a surface of the cutting blade includes three sections including a portion of a rake face, a portion of a flank face, and a ridge line at which the portion of the rake face and the portion of the flank face cross,
• the diamond part has a region A,
• the region A is a region that is present bridging over the three sections, which are the portion of the rake face, the ridge line, and the portion of the flank face on the surface of the cutting blade, and
• the region A has a surface roughness Ra of not more than 0.2 μm,
• wherein the diamond part has a size that fits entirely inside a cylindrical shape defined by a diameter of 3 mm×a length of 20 mm,
• the diamond part is made of a single crystal diamond or a binderless polycrystalline diamond,
• the region A has a concentration of tungsten element of not less than 0.03 mass % and not more than 0.9 mass % where the diamond part is made of the single crystal diamond, and
• the region A has a concentration of tungsten element of not less than 0.02 mass % and not more than 0.95 mass % where the diamond part is made of the binderless polycrystalline diamond.