  We present high quality near infrared Color Magnitude Diagrams of 10 Galactic
Globular Clusters (GCs) spanning a wide metallicity range (-2.15<[Fe/H]<-0.2).
This homogeneous data-base has been used to perform a detailed analysis of the
Red Giant Branch (RGB), adopting a variety of observables to describe its
physical and chemical properties.
  First, a set of metallicity indicators have been measured, namely: (i) the
RGB (J-K) and (V-K) colors at different magnitude levels; (ii) the RGB K
magnitude at different colors; (iii) the RGB slope. For these parameters we
present new calibrations in terms of both spectroscopic iron abundance and
global metallicity, including the alpha-element enhancement. These relations
can be used to derive a photometric estimate of the GC metal content from the
RGB morphology and location.
  Second, the location in luminosity of the main RGB features (namely, the Bump
and the Tip) and their dependence on metallicity have been studied, yielding
quantitative observational relationships.
  Finally, adopting new transformations between the observational and
theoretical quantities, the mean ridge lines for the clusters of our sample
have been reported in the (M_Bol, Log(T_e)) plane. This allows to study the RGB
location in terms of effective temperature, bolometric luminosity of the main
RGB features, and their calibrations with varying metallicity. Direct
comparisons between up-dated theoretical models and observations show an
excellent overall agreement.
