According to Leslie Fields book The Queen's Jewels (pages 101 and 103 of the 2002 publishing), "when King George V celebrated his Silver Jubilee, on 6 May 1935, he gave his two granddaughters their first serious jewellery: pearl necklaces. Princess Elizabeth was given three perfectly matched rows, and Princess Margaret, being four years younger, two rows. The Princesses (...) wore their pearls for their parents' Coronation two years later...". It is not explicitely said that the Princesses wore their necklaces for the Jubilee celebrations.
Here are a few pictures from King George V's Silver Jubilee celebrations. Unfortunately, it is almost impossible to see whether the young princesses are wearing their necklace or not.
The carriage procession:
The balcony scene:
The service at Saint Paul's Cathedral (oil on canvas, by Frank Owen Salisbury - courtesy of Guildhall Art Gallery) :
(pictures sources: Daily Mail, Pinterest, Saint Paul's Cathedral's website)
--Previous Message-- : There is the story that Princess Margaret was : upset that she was to wear two strands of : pearls, while Princess Elizabeth was to have : three strands. Their outfits for the : Coronation of their father were otherwise : identical. This led me to believe that the : pearl necklaces were created for the : Coronation. Did the little princesses also : wear them for their grandfather's Jubilee?? :