A hidden weekly gemstone market sits in a narrow Hanoi alley, Alley 456 on Hoang Hoa Tham Street, Ngoc Ha Ward. It opens only on Sundays from 8:30 am to 3 pm, offering a special way to shop for stones.

Buyers bring magnifying glasses and specialist lights to check each stone. They use the tools to tell real stones from imitations and to look at colour intensity, transparency and scratches. This careful inspection helps them decide the quality.

Prices at the market vary enormously. Shopper Ha Kim Ngan said some pieces cost just tens of thousands of dong, while others sell for millions, hundreds of millions or even billions. One trader valued a finished ruby ring at VND 80 million (about $3,000), and many visitors—collectors, tourists and experienced traders—spend hours, sometimes a whole day, examining stones before buying.

Local traders note that the market started about a decade ago with only a few stalls and was first a meeting place for dealers and jewelers. It has grown into a lively Sunday market where anyone can handle and learn about gemstones.