Amethysts

Amethysts are well represented in the royal families of Europe; with hues ranging from light purple to deep, vibrant purple. The most magnificent set of amethysts, at least according to this humble author, belongs to the Swedish royal family. The amethysts, which are part of the Bernadotte Family Foundation, date to the first French Empire. They were originally the property of the Empress Josephine, who in turn gave them to Princess Augusta Amalia of Bavaria when she married Josephine’s son, Eugene de Beauharnais, Duke of Leuchtenberg. 
heir daughter Josephine of Leuchtenberg married Crown Prince Oscar of Sweden, later becoming Queen of Sweden. Incidentally, Oscar was the son of King Charles XIV John of Sweden and his wife Désirée, who was originally engaged to Napoleon Bonaparte; she had broken it off upon meeting the man she would eventually marry, becoming the Queen Consort of Sweden and Norway.

wiki/Josephine of Leuchtenberg
wiki/Oscar_I_of_Sweden

Upon her marriage to Crown Prince Oscar, Josephine brought with her an astounding collection of jewels, which included the Swedish sapphire parure, the emeralds which are now part of the Norwegian royal jewel collection, and the amethysts. The original demi-parure consisted of a necklace, pendant earrings, two bracelets, a brooch, and a corsage ornament. Queen Silvia later had the necklace mounted on a tiara frame, and the two bracelets combined with the corsage ornament to create a necklace. This provided the Swedish royal family with an amethyst tiara, necklace, pendant, brooch, and earrings. This set comprises exquisitely large amethysts of the deepest and most desirable shades of purple which are set in gold, surrounded by diamonds set in silver. Queen Silvia wore the amethysts to the wedding of the Crown Prince of Denmark (here) and to the 1984 Nobel Prize award ceremony (here);  

Crown Princess Victoria  has also worn them (she is seen here wearing the tiara and earrings, and here wearing the necklace without the drop pendant, together with the brooch and earrings). the royal universe