In October 2013, Kate was seen wearing this gold plated necklace.
It was evidently gifted to her in honor of her new son, Prince George.
It features three charms: A small heart shaped charm with the letter W (presumably for William), a round charm with her son’s full name: George Alexander Louis, and a charm shaped like a small boy.
The necklace is customizable in many ways. There is a sterling silver option for those who don’t want gold, the length can be shortened or elongated, and both sides of the charms can be engraved.
Here it is on Kate.
She wore it while out shopping. I would love to see her wear this again, hopefully with a charm for Charlotte.