Diamond is characterised by its exceptional hardness, robustness and its optical and thermal properties; pre-eminent as a gemstone and an industrial tool. Natural diamond has an inherent variability and scarcity that limits its use in engineering applications. Developments in synthesis processes have enabled the production of consistently engineered synthetic diamond; firstly in the 1950s using high pressure and high temperature. The advent of practical chemical vapour deposition (CVD) in the 1980s, with steadily improving control over defects, has enabled the creation of new grades of synthetic CVD diamond, where the properties are engineered for specific technological applications, from industrial lasers, thermal management of power electronics to emerging ones in industrial electrochemistry and sensors. This talk will briefly overview the progress made in manipulating these defects, how they influence the properties of synthetic diamond and some of the extraordinary applications that have been enabled by this progress.