Quin, Henry (1717–91), medical doctor and lapidary, was probably born in Dublin, one of two sons and one daughter of Thomas Quin (d. 1767), an eminent apothecary in the city, and Isabella Quin (née Brownrigg), daughter of Henry Brownrigg, of Annagh, Gorey, Co. Wexford. He was educated in a school in Golden Lane, and after 1724 in Abbey St. by the Rev. L. Henry Young. He studied at TCD (1733–7), graduating with a BA. Examined before the King and Queen's College of Physicians, Dublin (1742/3), he was admitted MB of TCD (1743). He then seems to have left for Italy, as he returned to Dublin in 1749 as a doctor of medicine of Padua university. A quarto manuscript volume (c.1747), comprised of Latin notes dealing with chemistry and medical matters, was probably used by him during his study in Italy. In 1750 he was elected king's professor of the practice of medicine in the school of physic of TCD; in the same year he was conferred by TCD with an MD. Admitted a candidate of the RCPI in 1750, he was elected a fellow in 1754. Establishing a lucrative medical practice in Dublin, in 1750 he attended Mary Delany (qv), the wife of Dr Patrick Delany (qv) – both of whom had been prominent in the circle surrounding Jonathan Swift (qv) – at Delville, their home in Glasnevin. Registrar of the RCPI (1755–6), Quin was elected president of the college six times from 1758 to 1781; he was also college treasurer at various times from 1767 to 1780. An amateur musician, he played the harpsichord in the musical academy on Fishamble St., founded in 1757 by Lord Mornington. In 1763 he purchased a large house at 101 St Stephen's Green from William Fairbrother, of Foxhall, Co. Wicklow. A century later the house would become the institute for training female servants, and afterwards St Patrick's nurses’ home.
Although Quin did not contribute to any medical advancements, he promoted the development of modern medical teaching, and was a generous patron of the arts. While in Italy, he became interested in collecting ancient gems, such as cameos and intaglios, and he studied the method of making copies of gems using a glass paste, a process used by the ancient Romans. Setting up his own laboratory in Dublin, he devoted his spare time to studying the reproduction of gems. Making the acquaintance in 1763 of James Tassie (1735–99), a stone cutter and modeller, he employed him as his assistant. Together they invented a white enamel composition, a kind of vitreous paste, which Tassie later used for his gem imitations and to cast his wax medallion portraits. Tassie kept secret the nature of the glass composition, but later analysis showed it to be an easily fusible lead potash glass. Recognising Tassie's ability, Quin urged him to go to London, where he achieved considerable success. Quin met the medallist William Mossop (qv) (1751–1805), and became his patron and benefactor; in 1782 Mossop completed a medal portrait of Quin with the inscription ‘Henricus Quin MD’. Quin also patronised the seal cutter John Logan (1750–1805), who made a cameo portrait of him from Mossop's medal, which was later reproduced in glass by Tassie.
In 1771 Quin purchased a property at Borleigh, Co. Wexford, for £13,000, where he entertained his friends and engaged in expensive hobbies. A poem written by poet and physician John Gilborne in 1775 described Quin thus: ‘He teaches youth the cure, the remedies / And various causes for all maladies; / The speculative theoretic rule / And the best practise, in the physic school’ (quoted in Kirkpatrick, 28). On his resignation as president of the RCPI in 1782, he was elected an honorary fellow. He was an original subscriber to the Bank of Ireland in 1783, giving £5,000. His duties as king's professor at TCD did not occupy much of his time, but he retained the position and the annual salary of £926 until 1786. Quin married (1753) Anne Monck, a sister of Harry Monck, who had married a daughter of the first duke of Portland; they had three sons and three daughters. On his wife's death in 1788 he acquired a considerable fortune. He had many holdings in Dublin, including houses on Linen Hall and Molesworth streets, and also owned an estate in Ballygonnell, Co. Wicklow. He died at his St Stephen's Green home on 11 February 1791, reputedly leaving property to the value of £70,000 in his will. A marble bust portrait is in the RCPI. His son Charles William Quin (d. 1818), a physician at the Royal Hospital, Kilmainham, conducted preliminary research into tuberculous meningitis. Another son, Henry George Quin, travelled extensively, and bequeathed a collection of rare books, the ‘Bibliotheca Quiniana’, including fourteen incunabula, to the manuscript room of TCD; he committed suicide in 1805.