I present and discuss the definition of a "clock" able to rank star clusters as a function of their stage of dynamical evolution, and a "scale" able to weigh stars and efficently pinpoint heavy objects in a photometrically indistinguishable population of low mass stars. These tools have been specifically designed in the context of understanding the physics of Blue Straggler Stars (BSSs). In turn, this special class of exotic objects is a powerful gravitational probe of the internal dynamical evolution of star clusters.