There usually are many superfluous things to jewellery. Too many. Sometimes it is too ostentatious; some other times, it shows too much formal complexity. It is usually gratuitous, affected, muddled or lavish.
And we shun lavishness. We believe jewels should comprise only the bare essentials . The necessary elements, solely and exclusively. Magic, beauty, permanence, subtlety, imagination... They should be able to transmit in the simplest way.
Lacking nothing, wanting nothing. Consisting only of the main, essential elements.