Graphene particulates, especially graphene nanoribbons (GNRs) and graphene quantum dots (GQDs), and a high-throughput process for the production of such particulates is provided. The graphene particulates are produced by a nanotomy process in which graphene blocks are cut from a source of graphite and then exfoliated into a plurality of graphene particulates. Graphene particulates having narrow widths, on the order of 100 nm or less, can be produced having band gap properties suitable for use in a variety of electrical applications.