Abstract: A method of measuring a concentration of nitrogen in diamond includes a first step, a second step, and a third step. In the first step, diamond is arranged in the inside of an integrating sphere. In the second step, visible light is emitted to the inside of the integrating sphere and the visible light that is reflected by an inner surface of the integrating sphere and passes through or is reflected by diamond arranged in the inside of the integrating sphere is received. In the third step, the concentration of nitrogen in diamond is calculated based on data on received visible light and a mass of diamond.

Abstract: A cutting tool comprises a rake face and a flank face, the cutting tool being composed of a substrate made of a cubic boron nitride sintered material and a coating provided on the substrate, the coating including a MAlN layer, the MAlN layer including crystal grains of MxAl1-xN in the cubic crystal system, nF<nR being satisfied, where nF represents a number of voids per 100 ?m in length of the MAlN layer on the flank face in a cross section of the MAlN layer, and nR represents a number of voids per 100 ?m in length of the MAlN layer on the rake face in a cross section of the MAlN layer, nD being 3 or less, where nD represents a number of droplets per 100 ?m in length of the MAlN layer on the flank face in a cross section of the MAlN layer.

Abstract: A cutting tool comprises a rake face and a flank face, the cutting tool being composed of a substrate made of a cubic boron nitride sintered material and a coating provided on the substrate, the coating including a MAlN layer, when a cross section of the MAlN layer is subjected to an electron backscattering diffraction image analysis to determine a crystal orientation of each of the crystal grains of the MxAl1?xN and a color map is created based thereon, then on the color map, the flank face having the MAlN layer occupied in area by 45% to 75% by crystal grains of the MxAl1?xN having a (111) plane with a normal thereto extending in a direction within 25 degrees with respect to a direction in which a normal to the flank face extends, the MAlN layer having a residual stress of ?2 GPa to ?0.1 GPa.

Abstract: A cutting tool comprises a rake face and a flank face, the cutting tool being composed of a substrate made of a cubic boron nitride sintered material and a coating provided on the substrate, the coating including a MAIN layer, the MAIN layer including crystal grains of MxAl1-xN in the cubic crystal system, nF<nR being satisfied, where nF represents a number of voids per 100 ?m in length of the MAIN layer on the flank face in a cross section of the MAIN layer, and nR represents a number of voids per 100 ?m in length of the MAIN layer on the rake face in a cross section of the MAIN layer, nD being 3 or less, where nD represents a number of droplets per 100 ?m in length of the MAIN layer on the flank face in a cross section of the MAIN layer.