An emerald diamond and pearl brooch from the 19th century.

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The stone, named Tiffany Diamond, is truly a masterpiece. In 1877, a rough diamond of 287.42 carats was discovered in South Africa, and one year later, Charles Lewis Tiffany, founder of the label, purchased it. He then sent it to Paris. Craftsman cut it to 128.54 carats, making it one of the largest and finest yellow diamonds, and it was later officially named Tiffany Diamond.

"What came out from that incredible rough was this advanced cutting technique of the diamond. When you look at it now, it looks like it was cut only yesterday," says Melvyn Kirtley, chief gemologist of Tiffany & Co.

Because it is so rare, only legendary actress Audrey Hepburn has ever wore it for publicity photographs for Breakfast at Tiffany's in 1961, and since then, it was exhibited in Tiffany & Co's Fifth Avenue store in New York.

"It doesn't travel much. It goes out from our store very occasionally, for special reasons. We have important events and clients in Beijing right now, and we really felt it is necessary to bring Tiffany Diamond to China, to illustrate how important Chinese market is to us," Kirtley says.

"(Being here) means a lot to our brand, and it means a lot to our Chinese customers. The diamond has been in Tiffany for the entire history. It is very much part of our brand," he adds.

Kirtley deals with Tiffany's important clients around the world. According to him, China has a growing Tiffany fan base.