Diamond is an exceptional material that has recently seen a remarkable increase in interest in academic research and engineering since high-quality substrates became commercially available and affordable. Exploiting the high refractive index, hardness, laser-induced damage threshold, thermal conductivity and chemical resistance, an abundance of applications incorporating ever higher-performance diamond devices has seen steady growth. Among these, diffractive optical elements stand out-with progress in fabrication technologies, micro- and nano-fabrication techniques have enabled the creation of gratings and diffractive optical elements with outstanding properties. Research activities in this field have further been spurred by the unique property of diamond to be able to host optically active atom scale defects in the crystal lattice. Such color centers allow generation and manipulation of individual photons, which has contributed to accelerated developments in engineering of novel quantum applications in diamond, with diffractive optical elements amidst critical components for larger-scale systems. This review collects recent examples of diffractive optical devices in diamond, and highlights the advances in manufacturing of such devices using micro- and nano-fabrication techniques, in contrast to more traditional methods, and avenues to explore diamond diffractive optical elements for emerging and future applications are put in perspective.