This work presents an overview of the different topologies of Coaxial Magnetic Gears (CMG) reported in the literature, highlighting their advantages and limitations both in comparison with each other and with their mechanical counterparts, namely planetary gears. Among the available configurations, particular attention is devoted to the topology employing Buried-Mounted Permanent Magnets (BM), which is especially suitable for high-speed applications due to its improved mechanical robustness and rotor integrity. A three-dimensional model of this BM-CMG topology was developed in SIMULIA Opera 3D and used to perform electromagnetic simulations aimed at evaluating the maximum transmissible torque, the magnetic flux density distributions and the eddy-currents distributions within the permanent magnets.