Diamonds are a girl’s best friend—especially when they’re attached to a stunning sapphire. 

Fans of both will get the chance to bid on this one-of-a-kind necklace at a Phillips sale held in Hong Kong on May 23. Crafted in 2004, the showstopper is headed to auction for the first time from a private collection. Its starring attraction, the unheated cushion-shaped sapphire at its center, weighs a whopping 118.5 carats, making it one of the largest sapphires to reach auction in the three decades. 

The massive stone hails all the way from gem-rich Sri Lanka and comes with SSEF and Gübelin gemmological reports, as well as an appendix letter that details the sapphire’s rarity. Awarded 98 out of 100 Gübelin points, it’s considered to be an “exceptional” grade. Gübelin Gem Lab gave the stone its royal blue color grading, thanks to its even saturation, which is rarely seen in unheated blue sapphires of its size. The diamond arrangement surrounding the gem, meanwhile, echos earlier Bulgari designs from the thirties and fifties. 

Each circular link of the necklace is formed by tapered baguette diamonds, as opposed to brilliant-cut alternatives. The links are connected by pear-shaped diamonds at points, which keeps the seemingly hefty piece feeling fairly lightweight. Its repeating links mirror Bulgari’s modulo jewelry designs as well, in which parts are produced in a series and connected later on. The brand’s unique piece will lead the Hong Kong Jewels & Jadeite Sale at Phillips’s new headquarters in Asia, and it’s estimated to fetch between US$3.2 million (HK$25.12 million) and US$4.5 million (HK$35.32 million).

“Phillips is truly honored to bring this exceptional and impressive sapphire and diamond necklace by Bulgari to auction,” says Benoît Repellin, Phillips’s worldwide head of jewelry, in a statement. “Unique in its size, color, and origin, the [sapphire] stone embodies the transparency and luminosity pursued by Bulgari for its High Jewelry creations. This jewel is a holy grail for any collector, with a classic and elegant design typical of Bulgari that emphasizes the beauty and extraordinariness of the gem.” 

The sapphire is so memorable that Lucia Silvestri, Bulgari’s jewelry creative and gems buying executive director, can recall when she first held the gem over 20 years ago. “I was so impressed and touched that I still remember the emotion I felt.” The jeweler’s one-of-a-kind necklace was featured in its “125 Years of Italian Magnificence” retrospective in China from 2011 to 2012.

Want to view the whopping sapphire for yourself? The necklace will be displayed at Phillips in Hong Kong’s West Kowloon Cultural District from now until March 31. After leading the auctioneer’s Hong Kong Jewels & Jadeite Sale on May 23, it will embark on an international tour to New York, Singapore, Taipei, and Geneva from April 6 through May 15.