  We study the effect of citrate to gold molar ratio (X) on the size of
citrated gold nanoparticles (AuNPs). This dependence is still a matter of
debate for X $\ge$ 3 where the polydispersity is yet minimized. Indeed, there
is no consensus between experiments proposed so far for comparable experimental
conditions. Nonetheless, the sole available theoretical prediction has never
been validated experimentally in this range of X. We show unambiguously using 3
techniques (UV-Vis spectroscopy, dynamic light scattering and transmission
electronic microscopy), 2 different synthetic approaches (Direct, Inverse) and
10 X values for each approach that AuNPs' size decay as a monoexponential with
X. This result is, for the first time, in agreement with the sole available
theoretical prediction by Kumar et al. on the whole studied range of X.
