Flash Sale ONYX Rewards 10th Anniversary up to 36% Discount, Onyx Hospitality. More Welcome to ONYX - ONYX Hospitality Group is one of Southeast Asia's leading management companies encompassing an extensive portfolio of hotels & resorts, serviced apartments, spas and restaurants under brands including Amari, OZO and Shama. Established under one of Thailand's largest conglomerates Italthai Group, ONYX aspires to be the best medium sized management company in Southeast Asia. Our ethos is a commitment to develop quality partnerships through tailored hospitality management. Book Now and Get Best Offer for Your.