Diana's circle plate was etched with "William" and was a gift from Prince Charles after the birth of their son in 1982. Meanwhile, it's reported that Pippa bought Kate her own version from London boutique Merci Maman, confirmed on a company blog post:
"Family was one of the closest things to Diana's heart so it's no surprise that This shone through in her jewelery, featuring personalized pieces and meaningful charms . . . In 2013, Pippa Middleton continued This family tradition by giving her sister Kate, The Duchess of Cambridge, our Personalized Duchess Necklace to celebrate the birth of Prince George. Featuring a hand-engraved disc with the Prince's full name, a small boy charm and a heart engraved with a 'W' to represent Prince William."
Read on to get a closer look at both sentimental chains on Kate and Diana, then shop the exact design should you want to start the trend in your own family.