मणिमध्योऽर्धमाणवकः ॥ कZ_०२.११.१९ ॥
maṇimadhyo 'rdhamāṇavakaḥ
A necklace with a central gem is an “ardha-māṇavaka” (a half-graded subtype within the māṇavaka classification).
To encode intermediate quality/value bands so that pricing, wages, and procurement can match finer differences in material/workmanship.
It reduces ambiguity—sellers cannot pass a lower grade as a higher one when categories are officially defined.