No. The crowns of the Queen consorts are considered private property of the Queens. Not part of the crown jewels; they are simply displayed alongside the other jewels in the Tower of London.
Thus she was well within her right to take her crown to India, to be worn at the Delhi Durbar; however in the end it was decided that Queen Mary should have a new Parure made for the occasion.
--Previous Message-- : as part of the "Crown Jewels" HMQ : Mary's crown wasn't allowed to leave the : British Isles, and therefore a new piece was : created for the occasion, funded by the : Indian Office for the event. : : Isn't this the case? Not through choice of : diplomacy, but a fundamental House : principle. : : As for the Koh-I-Noor, I'm confused as to : why there's this fable that it's been : stolen, even when handed to Ranjit Singh by : HMQ Victoria, he took pleasure in personally : 'giving' it to her himself. Surely that : would quash any ideas of it being stolen or : appropriated by coersion. : : --Previous Message-- : : Far too blatant. : : By and large the royals get the diplomacy : right. : : : --Previous Message-- : And there no doubt would have been comments : and complaints if she'd left it at home and : worn the crown to the Durbar without it. : : : : :