The Coloured Gemstone Working Group (CGWG), unites luxury brands and mining companies with a common interest in catalysing positive change in the responsible sourcing of coloured gemstones.In 2015, Tiffany & Co., Swarovski, Richemont, LVMH, Kering and Gemfields formed the CGWG. The Muzo Companies joined in 2017 and Chopard in 2019.