SINGLE CRYSTAL SYNTHETIC DIAMOND MATERIAL VIA CHEMICAL VAPOUR DEPOSITION

There is described a single crystal CVD diamond material comprising three orthogonal dimensions of at least 2 mm; one or more regions of low optical birefringence, indicative of low strain, such that in a sample of the single crystal CVD diamond material having a thickness in a range 0.5 mm to 1.0 mm and an area of greater than 1.3 mm×1.3 mm and measured using a pixel size of area in a range 1×1 μm2 to 20×20 μm2, a maximum value of Δn[average] does not exceed 1.5×10−4 for the one or more regions of low optical birefringence, where Δn[average] is an average value of a difference between refractive index for light polarised parallel to slow and fast axes averaged over the sample thickness; one or more regions of high optical birefringence, indicative of high strain, such that in said sample of the single crystal CVD diamond material and measured using said pixel size, Δn[average] is greater than 1.5×10−4 and less than 3×10−3; and is wherein every 1.3 mm×1.3 mm area of the sample of the single crystal CVD diamond material comprises at least one of said regions of high optical birefringence. There is also described a method of making the CVD diamond material.