Abstract: A superhard polycrystalline construction comprises a body of polycrystalline superhard material formed of a mass of superhard grains exhibiting inter-granular bonding and defining a plurality of interstitial regions therebetween, and a non-superhard phase at least partially filling a plurality of the interstitial regions and having an associated shape factor of greater than around 0.65 and a substrate bonded to the body of superhard material along an interface, the substrate having a region adjacent the interface comprising hinder material in an amount at least 5% less than the remainder of the substrate.

Abstract: A single crystal CVD diamond material is disclosed, the material comprising a total nitrogen concentration of at least 3 ppm as measured by secondary ion mass spectrometry (SIMS); and a low optical birefringence such that in a sample of the single crystal CVD diamond material having an area of at least 1.3 mm×1.3 mm, and measured using a pixel size of area in a range 1×1 ?m2 to 20×20 ?m2, a maximum value of ?n[average] does not exceed 1.5×10?4, where ?n[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. A method of making the material is also disclosed.

Abstract: A superhard polycrystalline construction comprises a body of polycrystalline superhard material formed of a mass of superhard grains exhibiting inter-granular bonding and defining a plurality of interstitial regions therebetween, and a non-superhard phase at least partially filling a plurality of the interstitial regions and having an associated shape factor of greater than around 0.65 and a substrate bonded to the body of superhard material along an interface, the substrate having a region adjacent the interface comprising binder material in an amount at least 5% less than the remainder of the substrate.