As a “messenger” from the deep Earth, the geoscience community has long been intrigued by the formation temperature, pressure, and crystallization medium of natural diamonds. The various morphology and surface characteristics of these diamonds serve as invaluable records, shedding light on their crystallization, medium, and migration processes. With recent advancements in high- temperature and high- pressure (HPHT) techniques, as well as the industrial production of synthetic diamonds, we now have the means to extensively investigate the morphology of synthetic diamonds and their relationship with temperature, pressure, and composition. In this paper, we present a comprehensive comparative morphological review of synthetic diamonds grown under various conditions, as well as different types of natural diamonds. Our goal is to enhance our understanding of the P- T parameters and mantle fluid composition associated with the crystallization of natural diamonds. By conducting this review, we aim to provide valuable insights into the recovery of chemical composition in carbon- bearing fluids/melts within the deep Earth, especially under complex geological backgrounds. Additionally, we seek to gain a deeper understanding of the formation environment of natural diamonds and the subsequent corrosion reaction processes.