Charles Sew Hoy was known to Chinese as Choie Sew Hoy, Choie being his clan name. He signed himself Sew Hoy in English, and this became his English surname. He was born probably between 1836 and 1838. His father, Choie Bing Some, was a farmer of Sha Kong (She Gang) village, north of Canton (Guangzhou) in the upper district of Panyu county, Guangdong province, China; his mother's name is not known.
Sew Hoy went with other Cantonese gold-seekers to California, then to Victoria, and on to Otago, New Zealand, in about 1868 – two years after the arrival of the first Chinese mining parties. He opened a store in Dunedin in 1869 and developed into a successful merchant importing Chinese goods. Like other Chinese merchants in the city he became a social focus for the Chinese miners: providing advice, help and credit; outfitting and provisioning newcomers; and supplying Chinese stores in the goldfields. Sew Hoy was also twice reported to be exporting Jew's ear fungus ( Auricularia polytricha ) to China, despite his distance from the North Island forests where it grew.
Unlike most of his fellow Chinese, who saw themselves only as sojourners, Sew Hoy was naturalised in 1873. He did not, however, bring his wife to New Zealand, although a few Chinese wives began arriving in Dunedin from 1873. Virtually nothing is known of her except that her name was Young Soy May, and that her two sons, Kum Yok and Kum Poy, came to New Zealand. There was at least one other child, a daughter, who remained in China. At some point Sew Hoy and Eliza Ann (sometimes known as Eliza Lilly) Prescott began living together in a modest villa in Dunedin and had two children: Violet and Henry. It was presumably as a result of Eliza's influence that the children attended Anglican schools, since Sew Hoy probably never became a Christian. Eliza died on 15 February 1909, aged 40.
Sew Hoy became a prominent leader of Otago's Chinese miners, most of whom also came from the upper Panyu district; as one man put it: 'If Sew Hoy tell you a stone roll uphill, you believe him.' He commanded respect from Chinese and European alike, not least because he opposed opium smoking, and because his word was his bond. To Europeans he was well known for his 'interest in public affairs.… As everyone knows, his name invariably figured on subscription lists'. Being bilingual, he was able to mix in European society, and joined St John Kilwinning Lodge of the Freemasons. By the early 1880s he was the best-known Chinese in Dunedin.
Sew Hoy's reputation spread, particularly because of his goldmining investments. He had 11 known mining interests, most notably in gold dredging. In 1887 he acquired 140 acres at Big Beach, a gold-bearing flat of about 250 acres on the Shotover River. Its surface ground had been worked over but Chinese miners had told Sew Hoy of the potential of its waterlogged deeper layers. In 1888 he decided to dredge Big Beach, although gold dredging was in its infancy and dredge design was still being pioneered. Previous dredging attempts had only limited success because the machinery used was faulty in design.
Sew Hoy formed the Shotover Big Beach Gold Mining Company in 1888. He held 146 of the 300 shares; Kum Yok was another shareholder, and the remainder were Europeans. After watching the Dunedin harbour dredge at work Sew Hoy ordered one of a similar type. In 1889 the 'Sew Hoy dredge' was working successfully on ground even 'quite away from the river'; it was designed for working the river flat as well as the bed. Its remarkable returns – as much as £40 for one day's dredging – created a 'dredging fever' which resulted in Otago's first gold-dredging boom from 1889 to 1891. Sew Hoy was regarded as the chief figure of the Shotover company, which not only opened up river flats to dredging but also firmly established dredging as a commercially feasible and profitable branch of goldmining.
The company was reorganised in 1889 as the Sew Hoy Big Beach Gold Mining Company. It built three more dredges and was the principal New Zealand gold-dredging company until 1897. It chose voluntary liquidation in 1897 after Big Beach was worked out. By this time, however, numerous companies were following Sew Hoy's lead, especially after the Electric Gold Dredging Company struck sensational returns on the Kawarau River. Dredging in fact led Otago's mining (and provincial) revival and ultimately won about one-third of its total gold production. The Sew Hoy dredge became the direct prototype of the New Zealand gold dredge, which itself became the leading gold-dredging design in the world.
From 1894, however, Sew Hoy and Kum Poy were concentrating on extensive hydraulic sluicing and elevating at Paddy's Alley, Nokomai, in north-west Southland. Here too they were perceptive and innovative and used a workforce of both Chinese and Europeans. Nokomai had been almost deserted when they arrived, but by 1895 news of Sew Hoy's initiatives led to a rush of new mining applications, 'dazzling' promises and a sustained mining revival in northern Southland. By 1898 Sew Hoy and his son had spent £15,000 and needed another £6,000. Consequently, in 1898 they floated the Nokomai Hydraulic Sluicing Company with themselves as the major shareholders; for many years the company was the top registered sluicing concern in New Zealand.
Sew Hoy proved decisively that nineteenth century New Zealand Chinese had the capacity and ability to undertake advanced mining projects, and could successfully enter the European world. Yet he did not abandon his Chinese traditions. The Cheong Shing Tong – the benevolent society of Panyu and Hua migrants which operated from his store – helped the poor and elderly. In 1883 the society was responsible for exhuming 230 Chinese dead and conveying them to Guangdong. Sew Hoy died on 22 July 1901 at Dunedin, where he was buried. His body was disinterred in 1902 during another mass exhumation and placed on board the Ventnor, bound for China. Unfortunately the ship sank off Hokianga, and his remains, along with most of the other 498 bodies, were lost. It is still remembered, however, that he wished to be buried in the Cheong Shing Tong's cemetery in upper Panyu, with the bodies of otherwise friendless former associates buried around him.