IGCP-649 project "Diamonds and Recycled Mantle " (2015-2019) is aimed to carry out extensive and systematic research on the peridotites, chromitites, and related high pressure and reduced minerals such as diamond, moissanite and other unusual minerals, from different ophiolites and orogenic belts in the world, in order to understand the formation and origin of deep-mantle minerals in oceanic lithosphere, the origin of carbon for the ophiolite-hosted diamonds, the evolution of Earth's mantle and the dynamic process of ophiolite emplacement and also to provide new model for chromitite formation and exploration. Since 2015, the IGCP-649 workshops and field excursions have been held at the world well-known classic ophiolites and chromitites exposed areas, such as the North Qilian ophiolite in China (Yang et al., 2015a), the Troodos ophiolite in Cyprus (Yang et al., 2016), the Mayari-Baracoa ophiolites and chromitites in Cuba (Yang et al., 2017), the Massif du Sud ophiolite in New Caledonia (Yang and Shen, 2018), and the Semail ophiolite in Oman this year (2019). In addition to holding workshops and field excursions, the IGCP-649 project has also organized many scientific sessions on ophiolites and chromitites in world well-known international conferences, e.g., Goldschmidt Conference (2015, 2017, 2019), Annual Meeting of Geological Society of America (2015, 2017), the International Geological Congress (2016, 2020 now postponed), and published several special issues of the journals, such as Gondwana Research (2015), Lithosphere (2018), Earth Sciences (2019), as well as abstract volumes (2015, 2016, 2017, 2018, 2020) in the journal Acta Geologica Sinica. All these scientific activities and publications provided an excellent opportunity for international geologists and earth science communications to gather and exchange their new achievements and perspectives.