  The Gram matrix of a set of quantum pure states plays key roles in quantum
information theory. It has been highlighted that the Gram matrix of a
pure-state ensemble can be viewed as a quantum state, and the quantumness of a
pure-state ensemble can thus be quantified by the coherence of the Gram matrix
[Europhys. Lett. \textbf{134} 30003]. Instead of the $l_1$-norm of coherence
and the relative entropy of coherence, we utilize the generalized
$\alpha$-$z$-relative R\'enyi entropy of coherence of the Gram matrix to
quantify the quantumness of a pure-state ensemble and explore its properties.
We show the usefulness of this quantifier by calculating the quantumness of six
important pure-state ensembles. Furthermore, we compare our quantumness with
other existing ones and show their features as well as orderings.
