Complex sentence: So good were his copies that many of his friends believed them to be genuine; in 1946 de Hory sold a reproduction of a Picasso to a British friend who took it for an original.
Split into simpler sentences: So good were his copies that many of his friends believed them to be originals. In 1946 de Hory sold a reproduction of a Picasso to a British friend who took it for an original.