It's hard to make out but I believe the Grand Duchess was wearing a diamond brooch during the day. It features a leaf-y motif with berries.
She wore the same brooch to the gala dinner of the wedding of the Prince and Princess of Monaco, a state visit some years ago (from Portugal, if I recall correctly) and a number of other events I can't remember out of the top of my head.
--Previous Message-- : German Federal President Joachim Gauck is : currently paying a State Visit to the : Grand-Duchy of Luxembourg. : : Yesterday took place the State banquet at : Luxembourg's Grand-Ducal Palace. The : dresscode was black-tie/no decoration, : unfortunately. But the Grand-Duchess and : the Hereditary Grand-Duchess wore tiaras : anyway. : : Both ladies chose among the smallest tiaras : of the Grand-Ducal collection: Grand-Duchess : Maria-Teresa opted for the yellow topaz : tiara, while Hereditary Grand-Duchess : Stéphanie chose the amethyst parure: : : : : : : : : : : Earlier in the day, for the official welcome : of the President, Grand-Duchess Maria-Teresa : wore a small diamond brooch, that I can not : identify. Any idea? : : : : : : (pictures from the Grand-Ducal House's, of : Luxembourg's Government Press Service's, : Luxemburger Wort's and Tageblatt's websites) : : : : : :