Published online by Cambridge University Press: 20 November 2018
We study natural $*$-valuations,
$*$-places and graded
$*$-rings associated with
$*$-ordered rings. We prove that the natural
$*$-valuation is always quasi-Ore and is even quasi-commutative (i.e., the corresponding graded
$*$-ring is commutative), provided the ring contains an imaginary unit. Furthermore, it is proved that the graded
$*$-ring is isomorphic to a twisted semigroup algebra. Our results are applied to answer a question of Cimprič regarding
$*$-orderability of quantum groups.