We study the 3-jet decays of S- and P-wave quarkonia with C=+. If observed, some of these will offer a way of seeing the 3G vertex of QCD via 1S0, 3P0, 3P2(QQ) → GGG + Gqq → 3 jets. (As is well-known, cancellations reduce 3P1(QQ)→GGG.) We elaborate in detail the S-wave decay, as it is expected to show all the characteristic features of orthoquarkonium decays into 4 jets, 3S1(QQ) → GGGG + GGqq → 4 jets, which we will comment upon. These quarkonium decays offer a very clear signal for QCD as a non-abelian local gauge field theory with color-charged gluons.