 Complete the following phrase:  Paul Legrand 1840-1910 worked as the chief designer for the house of Boucheron from 1863-1867, and again 1871-1892. He is credited with the idea of combining pearls with diamond rondelles, first seen in Boucheron products in 1889. The rondelle cut of diamonds was pioneered by Bordinckx, who was also associated with Boucheron. While Legrand was head designer, in 1879, Boucheron developed a clasp-less necklace, which was part of its show which won a Grand Prix for Outstanding Innovation in a Jewellery Collection at the 