  A new classification system for carbon-rich stars is presented based on an
analysis of 51 AGB carbon stars through the most relevant classifying indices
available. The extension incorporated, that also represents the major advantage
of this new system, is the combination of the usual optical indices that
describe the photospheres of the objects, with new infrared ones, which allow
an interpretation of the circumstellar environment of the carbon-rich stars.
This new system is presented with the usual spectral subclasses and $C_2$-, j-,
MS- and temperature indices, and also with the new SiC- (SiC/C.A. abundance
estimation) and $\tau$- (opacity) indices. The values for the infrared indices
were carried out through a Monte Carlo simulation of the radiative transfer in
the circumstellar envelopes of the stars. The full set of indices, when applied
to our sample, resulted in a more efficient system of classification, since an
examination in a wide spectral range allows us to obtain a complete scenario
for carbon stars.
