A visitor checks the quality of a gemstone at the International Gem and Jewellery show in Colombo, Sri Lanka, on Aug. 29, 2019. The International Gem and Jewellery show, which is held from Aug. 29 to Sept. 1, draws hundreds of local and foreign exhibitors and a large number of influential trade visitors from around the world. (Photo by Gayan Sameera/Xinhua)

A necklace is on display at the International Gem and Jewellery show in Colombo, Sri Lanka, on Aug. 29, 2019. The International Gem and Jewellery show, which is held from Aug. 29 to Sept. 1, draws hundreds of local and foreign exhibitors and a large number of influential trade visitors from around the world. (Photo by Gayan Sameera/Xinhua)

An exhibitor shows his products to a visitor at the International Gem and Jewellery show in Colombo, Sri Lanka, on Aug. 29, 2019. The International Gem and Jewellery show, which is held from Aug. 29 to Sept. 1, draws hundreds of local and foreign exhibitors and a large number of influential trade visitors from around the world. (Photo by Gayan Sameera/Xinhua)

A necklace is on display at the International Gem and Jewellery show in Colombo, Sri Lanka, on Aug. 29, 2019. The International Gem and Jewellery show, which is held from Aug. 29 to Sept. 1, draws hundreds of local and foreign exhibitors and a large number of influential trade visitors from around the world. (Photo by Gayan Sameera/Xinhua)

People visit the International Gem and Jewellery show in Colombo, Sri Lanka, on Aug. 29, 2019. The International Gem and Jewellery show, which is held from Aug. 29 to Sept. 1, draws hundreds of local and foreign exhibitors and a large number of influential trade visitors from around the world. (Photo by Gayan Sameera/Xinhua)