We present Lick spectral indices for a complete sample of 139 candidate sup
er-metal-rich stars of different luminosity classes (MK type from I to V).
For 91 of these stars we were able to identify, in an accompanying paper, t
he fundamental atmosphere parameters. This confirms that at least 2/3 of th
e sample consists of stars with [Fe/H] in excess of +0.1 dex. Optical indic
es for both observations and fiducial synthetic spectra have been calibrate
d to the Lick system according to Worthey et al. and include the Fe I indic
es of Fe5015, Fe5270, and Fe5335 and the Mg I and MgH indices of Mg-2 and M
g b at 5180 Angstrom. The internal accuracy of the observations is found to
be sigma (Fe5015) = +/-0.32 Angstrom, sigma (Fe5270) = +/-0.19 Angstrom, s
igma (Fe5335) = +/-0.22 Angstrom, sigma (Mg-2) = +/-0.004 mag, and sigma (M
g b) = +/-0.19 Angstrom. This is about a factor of 2 better than the corres
ponding theoretical indices from the synthetic spectra, the latter being a
consequence of the intrinsic limitations in the input physics, as discussed
by Chavez et al.
By comparing models and observations, we find no evidence for nonstandard M
g versus Fe relative abundance, so [Mg/Fe] = 0, on the average, for our sam
ple. Both the Worthey et al. and Buzzoni et al. fitting functions are found
to suitably match the data and can therefore confidently be extended for p
opulation synthesis application also to supersolar metallicity regimes. A s
omewhat different behavior of the two fitting sets appears, however, beyond
the temperature constraints of our stellar sample. Its impact on the theor
etical output is discussed, as far as the integrated Mg-2 index is derived
from synthesis models of stellar aggregates. A two-index plot, such as Mg-2
versus Fe5270, is found to provide a simple and powerful tool for probing
distinctive properties of single stars and stellar aggregates as a whole. T
he major advantage, over a classical CM diagram, is that it is both reddeni
ng free and distance independent.