When the Princess of Wales returned to royal duties following chemotherapy treatment last year, fans quickly clocked that she had added a new eternity ring to her collection, believed to be Cartier’s Étincelle de Cartier wedding band. Over the past year, Kate has often been photographed wearing the $6,300 platinum ring, comprising 19 brilliant-cut diamonds and 19 brilliant-cut sapphires, in lieu of her more famous 12-carat oval-cut Ceylon sapphire engagement ring, which Prince William inherited from Princess Diana following her death.

There was much discussion about why the Princess was wearing her new Cartier ring—often paired with her wedding band and another diamond eternity ring, believed to have been gifted by William to mark Prince George’s birth in 2013—instead of her larger engagement ring. Perhaps it was simply a more everyday choice (Kate has tended to wear the latter at more formal events, such as last year’s Festival of Remembrance at Royal Albert Hall.)

But at Wimbledon at the weekend, Kate wore her engagement ring with both of her eternity rings, as well as her wedding band, for the first time. It comes as ring stacking is becoming increasing popular—particularly among new brides. “We’re increasingly seeing clients choose to style their eternity ring stacked with their engagement ring and wedding band, or wear it alone for a more relaxed look,” Eliza Walter, founder of Lylie Jewellery, tells Vogue. “In warmer months or during summer holidays, many opt to wear just their wedding band and eternity ring together—a combination that feels both effortless and meaningful.”

Of course, eternity rings are often deeply meaningful, traditionally bought to mark special milestones (there is speculation that Kate’s Étincelle de Cartier wedding band was gifted to her by William to mark their 13th wedding anniversary last year). “Eternity rings are a timeless symbol, a circle of precious metal traditionally set with stones all the way around, representing an unbroken bond and infinite commitment,” jeweler Rachel Boston explains. “The continuous line of diamonds or gemstones is a reminder that, like the ring itself, true love has no beginning or end.”

If Kate’s choice of jewelry at Wimbledon is anything to go by, it seems that the ring stacking trend isn’t going anywhere. All the better if each piece is imbued with sentimental value—a collection that’s been inherited or built up over the years.