 Octet and singlet in a fundamental SU3 tensor product

The tensor-product weight diagram has six distinct nonzero differences of the three defining weights and a zero weight of multiplicity three. Identify the tensor product with endomorphisms of ${\mathbb{C}}^3$ under conjugation. Its scalar line is a singlet, while the traceless matrices give the irreducible adjoint octet, with two zero weights. The root commutators connect all of the traceless matrix units, proving irreducibility rather than inferring it solely from a drawing.