From top left to bottom right: stellar radius, stellar density, stellar metallicity and stellar velocity dispersion as a function of stellar mass. Pale dots indicate the sub-samples defined by applying one selection criterion at a time using observable properties of present day GCs for stellar mass, dark matter and gas fraction, respectively (see Sect. 3.1). Stars and triangles represent the f_b = 1 and f_* = 1 samples, respectively. Stellar density is calculated assuming spherical symmetry, whilst the stellar velocity dispersion is calculated using the virial theorem (see Sect. 3.3). Corresponding quantities for Galactic GCs are overlaid as filled turquoise-coloured squares taken from McLaughlin & van der Marel (2005). Sizes for the f_b = 1 sample are upper limits due to the spatial resolution of the simulation. However, f_b = 1 objects show a separation from the general population of simulated objects at z = 6. They are in general more compact, dense, metal rich and have lower velocity dispersions due to a lack of dark matter.