  It is shown how the QED concept of a gauge-, scale- and scheme-independent
one-loop effective charge can be extended directly at the diagrammatic level to
QCD, thus justifying explicitly the ``naive non-abelianization'' prescription
used in renormalon calculus. It is first argued that, for on-shell external
fields and at the strictly one-loop level, the required gluon self-energy-like
function is precisely that obtained from S-matrix elements via the pinch
technique. The generalization of the pinch technique to explicitly off-shell
processes is then introduced. It is shown how, as a result of a fundamental
cancellation among conventional perturbation theory diagrams, encoded in the
QCD Ward identities, the pinch technique one-loop gluon self-energy
i\hat{\Pi}_{\mu\nu}^{ab}(q) remains gauge-independent and universal regardless
of the fact that the ``external'' fields in the given process are off-shell.
This demonstration involves a simple technique enabling the isolation, in an
arbitrary gauge, of i\hat{\Pi}_{\mu\nu}^{ab}(q) from subclasses of up to
several hundred diagrams at once. Furthermore, it is shown how this one-loop
cancellation mechanism iterates for the subclasses of n-loop diagrams
containing implicitly the Dyson chains of n one-loop self-energies
i\hat{\Pi}_{\mu\nu}^{ab}(q). The gauge cancellation required for the Dyson
summation of i\hat{\Pi}_{\mu\nu}^{ab}(q) is thus demonstrated explicitly in a
general class of ghost-free gauges for all orders n.
