On most of the portraits of Mary as Queen can be seen a pendant with a large drop pearl.

This pearl was a gift from Philip in 1554 before their marriage. The Marques de las Navas gave to Mary a 'great table diamond mounted in a superb gold setting, valued at 50,000 ducats; a necklace of eighteen brilliants worth 32,000 ducats; a great diamond, with a fine pearl pendant from it, worth 25,000 ducats, and other jewels, pearls, diamonds, emeralds, and rubies of inestimable value, for the Queen and her ladies.' (19th June,1554)

The pearl was found by a slave in the Pearl Islands in 1513. Vasco Nunez de Balboa the discoverer of the pacific ocean took the pearl and gave the slave his freedom. He sent the pearl to to Ferdinand V and it became one of the most prized of the Spanish crown jewels.

At Queen Mary's death the pearl was returned to Spain where it remained for over two hundred and fifty years. It was worn by all the queens-consort until 1808, when Napoleon took Spain and placed his brother Joseph on the throne. It was now that the pearl received the name of La Pelegrina - the Wanderer. When Joseph fled he took La Pelegrina with him and left it to his nephew, Prince Charles Louis Napoleon, afterward Napoleon III. While in exile in England, Napoleon III sold La Pelegrina to the 2nd Marquess of Abercorn. The pearl is very heavy and frequently fell from its setting. Twice the Duchess lost the pearl: once at a drawing-room at Buckingham palace, where three hours later it was recovered riding upon a lady's velvet court train, and again at Windsor, where three weeks later it was found in the cushions of a sofa. The second Duke had it bored to make it more secure, but this impaired its value.

It was owned by the Dukes of Abercorn until the later 20th century when it was purchased by Richard Burton for Elizabeth Taylor. They also, incidentily, owned this small famous portrait of Mary wearing La Pelegrina by Hans Eworth which they later gave to the National Portrait Gallery in London.