The link below is to a pdf version of an interesting 1975 ten page article on the Giuliano Family by the esteemed Geoffrey Munn.
See necklace displayed on page 5. Its description on page 6 says its from the Royal Collection and is an "Enamelled gold and multicoloured sapphire necklet", length = 16 inches.
There is no mention of zircons as stated in Leslie Field's description, and this is a choker necklace which doesn't match what Field wrote.
However the small green enamel leaves are very visible. I am guessing that Leslie Field's description had errors.