Pippa, 32, beamed as she stepped out in London, wearing a smile almost as big as the diamond on her finger. Just like 34-year-old Kate's engagement ring, once worn by Diana, Princess of Wales, the main stone is set in a halo of smaller diamonds.
Kate's features a 12 carat oval blue Ceylon sapphire surrounded by 12 solitaire diamonds, all set in 18 carat white gold. Although Pippa's ring bears a lot of similarities, it is decidedly more modern that her sister's.
Harry Brown, CEO at Chisholm Hunter, said of Pippa's ring: "James has made a very sophisticated choice in terms of the ring. It appears to be platinum and diamonds, possibly a ascher or cushion cut with a stunning round brilliant halo. This is a classic style which is as timeless as it is elegant, and is a simply stunning ring which Pippa will enjoy wearing every day."
For the ring's first official outing, Pippa ensured her manicure was perfect – again stealing inspiration from the Duchess, who wore a similar opaque colour on her nails so not to distract attention from the very important piece of jewellery.
Showing off her enviable figure, Pippa wore a pretty white Warehouse dress which she teamed with a tan satchel and matching sandals. The bride-to-be made no attempt to hide the ring from the waiting photographers, undoubtedly happy to share her happy news with the world.
The pictures of Pippa and her ring were taken outside the home she shares with James, brother of Made in Chelsea star Spencer. It's thought that the couple will tie the knot next year, and here's our predictions for what will definitely be one of the weddings of the year.