Gassan Singapore is a retail organisation specialising in the tourism industry.   Gassan Diamonds opened a Tax Free Watch Shop at Changi Singapore Airport in October 1999. In January 2017, Gassan Diamonds opened 2 more new stores in Changi Airport Terminal 4 which offer a luxury boutique from ultra-premium Swiss brand Tag Heuer, Cartier, Omega, IWC, Longines and Breitling.