Abstract: A method is provided for efficiently producing an entirely quality-controlled CVD diamond. A CVD process is interrupted at an early stage and the deposit is taken out of the reaction chamber, before a significant mass is accumulated, and is inspected by means of cathodoluminescence. The spectrum are compared with a given reference in terms of peak position, half width and 20%-value width in coordination. The observed deviation allows to determine whether to maintain or alter the settings.A diamond substance of acceptable quality which is properly specified in terms of the CL parameters is also provided.

Abstract: Making a diamond substance exhibiting a cathodoluminescence spectrum with the peak at a photon energy greater than 2.8 eV (electron volt), the half-value and 20%-value width not exceeding 0.5 eV and 0.8 eV, respectively, comprising: providing a substrate in a closed chamber, introducing a matrix gas comprising H.sub.2 and one selected from hydrocarbon and CO to said chamber, exciting the gas to create a plasma while heating said substrate to a temperature of at least 700.degree. C. and, thus, causing deposition and growth of diamond substance which is crystallographically diamond, controlling parameters of the deposition by means of the cathodoluminescence record and recovering the diamond substance from the chamber.

Abstract: Diamond abrasive comprising a mass of idiomorphic crystal grits which each have an irregular shaped core of diamond formed under pressure where diamond is thermodynamically favored phase, and a growth layer of diamond and/or diamond-like carbon formed over said core by chemical vapor deposition.