Amethyst intaglio : portrait of Constantius II wearing  military dress and a jewelled headband. About 360 AD.
Room 70, British Museum, GR 1907.5-14.1 ( Gem 2032 ).
<a href="//commons.wikimedia.org/wiki/User:Vassil" title="User:Vassil">Vassil</a>
<span class="int-own-work" lang="en">Own work</span>