The effects of thermal treatment and irradiation on the chemical properties of natural diamonds.

The modification of nitrogen-contaminated diamonds into color-enhanced diamonds is usually achieved by irradiation and thermal treatment (annealing). These treatments affect nitrogen contamination chemical bonding, vacancy concentration, and atom orientation centers in the diamond lattice. In this study, natural diamonds were subjected to irradiation and thermal annealing color enhancement treatments to produce green, blue, and yellow fancy diamonds.

Effect of Diamond Polishing and Thermal Treatment on Carbon Paramagnetic Centers' Nature and Structure.

Diamonds contain carbon paramagnetic centers (stable carbon radicals) in small concentrations (at the level of ~1 × 10 spins/mg) that can help in elucidating the structure of the nitrogen atoms' contaminants in the diamond crystal. All diamonds that undergo polishing are exposed to high temperatures, owing to the friction force during the polishing process, which may affect the carbon-centered radicals' concentration and structure. The temperature is increased appreciably; consequently, the black body radiation in the visible range turns orange.