  We examine the variations in the spectral characteristics and intensities of
PAHs in two different scenarios of PAH processing (or formation): (1) small
PAHs are being destroyed (or equivalently large PAHs are being formed, referred
to as SPR i.e. small PAHs removed), and (2) large PAHs are being destroyed (or
equivalently small PAHs are being formed referred to as LPR i.e. large PAHs
removed). PAH emission was measured considering both the presence or absence of
plateau components. The variation in the PAH band intensities as a function of
the average number of carbon atoms <N$_{C}$> has the highest dynamic range in
the SPR case suggesting that smaller PAHs have higher impact on the PAH band
strengths. The plateaus show overall declining emission with <N$_{C}$>, and
their higher dynamic range in the SPR case also suggests that smaller PAHs are
mainly contributing to the plateau emission. The 7.7/(11.0+11.2) $\mu$m PAH
band ratio presents the least amount of variance with the lowest dynamic range,
rendering this ratio as the better choice for tracing PAH charge. The
3.3/(11.2+11.0) $\mu$m PAH band ratio is the only ratio that has both a
monotonic variance and fully separated values among the SPR and LPR scenarios,
highlighting its efficiency as PAH size tracer but also allowing the
characterization of the dominant scenario of processing or formation in a given
region or source. We present new PAH charge $-$ size diagnostic diagrams, which
can provide insights on the average, maximum, or minimum N$_{C}$ within
astrophysical sources.
