Diamonds

characterized by their elegant tetrahedral arrangement of carbon atoms

exhibit outstanding thermal

mechanical

and electrical properties. In the fields of optics and photonics

diamonds are highly regarded for their exceptionally wide spectral transmission range

excellent thermo-optical properties

remarkable mechanical strength

and unique nonlinear optical characteristics. Recent advancements in chemical vapor deposition (CVD) technologies have enabled the production of synthetic diamonds with lower dislocation densities

reduced impurities

minimal residual stress

and low absorption coefficients

thereby meeting the stringent demands of optical applications

even under extreme conditions. Additionally

progress in diamond processing techniques—such as polishing

anti-reflection coatings

micro/nanostructuring

and color center engineering—has further enhanced the potential of optical-grade diamonds

expanding their applications in areas such as lasers

quantum technologies

and precision instrumentation. This review provides a comprehensive overview of recent research progress in diamond synthesis and processing technologies

with a focus on controlling dislocation density and impurity levels in optical-grade diamonds. Furthermore

it explores future development trends and advanced applications of diamonds

offering valuable insights and guidance for researchers dedicated to high-quality diamond crystal growth and its utilization.