The commission of the bust was a gift by pope Urban VIII, to be made by the Italian sculptor Lorenzo Bernini. Pope Urban hoped to coax the king into return to the Roman Catholic church. King Charles and queen Henrietta Maria were delighted with the bust, and gave Bernini a diamond ring in appreciation.
Van Dyck’s unusual portrait shows a solumn king — Charles the 1st was a short man, and from this portrait, a slender, delicate man. Eventually this triple portrait would outlive the bust it inspired, which burned in the Whitehall Palace fire of 1698. Van Dyck’s triple portrait is still visible in the Queen’s Drawing Room at Windsor Castle.
Reed Enger, "Charles I," in Obelisk Art History, Published February 23, 2016; last modified May 19, 2021, http://arthistoryproject.com/artists/anthony-van-dyck/charles-i/.