27th April and today’s Emerald tiara is part of the Danish Crown Jewels and is part of a set that also includes a necklace, earrings and a brooch. The jewels are on display at Rosenborg Castle. Only the Queen can wear these gems, and they can’t be taken out of the country. The emeralds date back to the 18th century. Queen Louise, mother of Britain’s Queen Alexandra was painted wearing the tiara. Queen Ingrid and Queen Margrethe are the only Queens who have been photographed wearing it.