|Photos: Raymond Reuter / Point de Vue / Getty Images|
While citrine is a variety of quartz whose colour ranges from a pale yellow to brown, topaz is a colourless and transparent stone usually tinted by impurities and thus available in an array of different colours. Whether a stone is a citrine or a topaz is notoriously hard to tell apart simply by looking at pictures as they largely only differ in hardness. Natural citrines, which mostly originate from Brazil, are rare but were pretty popular during the Art Deco period. Topazes, in general, would be a bit easier to come by and both pink and light blue topazes have been used in a number of royal and noble tiaras.
As it isn't commonly known where the Grand Ducal Family's [insert kind of yellow stone] and pearl tiara originally comes from, it is a bit hard to tell what the stone used might me. If I should make a guess, I would probably say it's topaz but simply because I think it would be easier to come by a larger number of equal yellow topazes and because the tiara doesn't look like Art Deco to me per se. However, I'm no expert and so it could just as easily be citrines.
|Photos: Corbis / Place Royale / Getty Images / Cour grand-ducale|
It wasn't seen after these outings for quite a while and only resurfaced when it was worn by Princess Margaretha during her parents 1999 state visit to Belgium. It vanished once again until Princess Alexandra got it out of the vault for National Day in 2011. Since then, it has been both worn by the Grand Duchess during a state visit to Germany in 2012 and by Hereditary Grand Duchess Stéphanie during Princess Madeleine's wedding in 2013. Grand Duchess Maria Teresa also sported parts of the parure for the wedding dinner of Archduke Christoph and Archduchess Adélaïde in December 2012.