<p>A cubic boron nitride cluster comprises a core ( 10 ) and an overgrown region, the overgrown region containing a plurality of cubic boron nitride crystallites ( 12 ) extending outwards from the core ( 10 ). The majority of the cubic boron nitride crystallites ( 12 ) have a cross-sectional area which increases as the distance from the core ( 10 ) increases. A method of producing cubic boron nitride clusters is also provided.</p>
