Compared to natural diamonds that are composed of a mixture of 12C and 13C isotopes, isotopically pure diamonds possess improved characteristics such as increased thermal conductivity.
[1] Thermal conductivity of diamonds is at a minimum when 12C and 13C are in a ratio of 1:1 and reaches a maximum when the composition is 100% 12C or 100% 13C.
[2] Such CO2 can be converted to methane and from there to isotopically pure synthetic diamonds.
[3] Isotopically enriched diamonds have been synthesized by application of chemical vapor deposition followed by high pressure.
[4] Isotopically pure 13C diamond layers 20 micrometers thick are used as stress sensors due to the advantageous Raman spectroscopy properties of 13C.