Unlike bulk particles, whose flows is usually highly dissipative, boundary particles can offer an excellent lubrication mechanism in between sliding surfaces. Examples include ball bearings, and more recently graphene flakes, fullerenes and fullerene-like nanoparticles that have shown superior lubrication properties: Graphene and other 2D materials exhibit structural superlubricity, a novel mechanism of ultralow friction occurring between clean, rigid crystalline surfaces due to atomic lattice misfit. While this phenomenon has sparked interest in applications for friction reduction, it has mainly remained a curiosity: most studies have been conducted in idealized conditions at the nanoscale, far away from practical applications. Here, we explore scaling superlubricity to macroscopic dimension using colloidal and granular particles coated with graphene. Using the coated particles confined between engineering surfaces of finite roughness, we investigate the resulting friction reduction at the macroscale as a function of parameters such as particle size, polydispersity, solvent and boundary conditions. The large size of the particles enables direct imaging of their structure during sliding of the surfaces, allowing us to connect their friction reduction to their structure under shear. We find that very low friction of graphene-coated particles suspended in glycerol correlates with their ordering within one or two lubricating layers. This ordering and the corresponding friction reduction get lost when the particles are squeezed out at higher applied load. These results offer insight into the structure-lubrication relationship of tribo-particles, and provide guidelines for the design of new particle-based lubricants.