ABSTRACT: Thermal Toughness Index (TTI) is a key factor in characterising diamond performances, so accurate testing of TTI value of diamond is very important. In this paper is analysed the influence of the heating mode and heating conditions upon the testing results. Some suggestions are given to ensure consistent, and reliable testing. A specially designed CYRI-1 tube type heating furnace and its excellent performances are introduced in the paper.

KEYWORDS: diamond, thermal toughness index, tube furnace, diamond heating