Perhaps some dates will help.
1. Waverley Ball, which you initially inquired about, was held in 1871.
2. The Silver Wedding Anniversary was in 1888.
3. Knightship found a valuable 1891 reference in the press.
That was significant as it solved the puzzle of who gave Queen Alexandra (and when) the tiara, which could take either the sapphire elements or the amethyst elements.
Knightship's find showed that the tiara, as well as the sapphire necklace, was given to Queen Alexandra by her brother-in-law and sister (the Emperor and Empress of Russia) in 1888.
Queen Alexandra wearing the tiara with the sapphire inserts in 1889.
4. Eventually, an amethyst necklace belonging to Queen Alexandra plus the tiara with amethyst elements and the sapphire necklace were inherited by Queen Alexandra's granddaughter, Princess Maud, Countess of Southesk. She wore the amethysts to the 1937 coronation. After her death all three jewels were auctioned.
1937 Princess Maud at coronation.