In the current technological era, the so-called quantum era, great efforts are directed towards the study and application of quantum materials in the most varied technological fields such as quantum information processing, cryptography as well as extreme-conditions sensors development. In this context, diamond finds a leading role as a host platform for quantum color centers. Particularly, the nitrogen-vacancy (NV) color center of diamond has been widely and successfully studied since the 2000s finding extensive use in many quantum devices, including magnetic imaging, quantum information processing as well as quantum repeaters required for long-distance quantum communications. Nevertheless, the emission of the NV center remains mainly in the phonon broadened line, which limits the efficiency of the spin-photon coupling. This limit can be overcome with centers combining a group-IV atom to a vacancy (G4V center) such as silicon-vacancy (SiV), germanium-vacancy (GeV), tin-vacancy (SnV) and lead-vacancy (PbV) centers, due to the protection induced by the symmetry of the G4V defects. This allows the G4V center luminescence to be concentrated at about 80% of the total luminescence in the zero-phonon line (ZPL). This special property still exists when G4V centers are integrated into nanodiamonds (NDs), allowing them to be efficiently coupled to microcavities for quantum optics and to be employed as single photon source. NDs containing G4V centers are also suitable quantum sensors for high-pressure experiments above megabar and for life science. Our recent studies have shown that microwave assisted chemical vapor deposition (CVD) is a reliable technique allowing the synthesis of high quality NDs in large quantities, without the need for seeds or a substrate, and with considerable degrees of freedom on the incorporation of group-IV impurities (Si and Ge) from a solid-state source into NDs, and on the control of their emissivity. These as-grown SiV- and GeV-NDs have been successfully tested as stress nano-sensors up to pressures of 180 GPa overcoming the reliability limits of traditional and even NV-based sensors. In this scientific context lies the NanoG4V project, which has three ambitious objectives: (1) to synthesise high-quality quantum grade CVD NDs containing G4V color centers with a stable and highly emissive ZPL; (2) to optimize the optical properties of the quantum grade G4V-NDs by high-pressure high-temperature (HPHT) annealing and surface treatments with the aim of reducing color center’s inhomogeneous line distribution close to homogeneous lifetime limit; (3) to control the number of embedded G4V centers per ND and to demonstrate the proof-of-concept sensing: (i) quantum magnetometry under Tesla range magnetic fields and (ii) quantum sensing at stress >100 GPa for extreme sensing experiments. This new generation of quantum-grade G4V CVD NDs will find a wide range of applications, even beyond the extreme-conditions sensing, for example in the field of nanoscale thermometry, live-cell dual-color imaging and drug delivery particle tracking for medical science, that currently rely only on NDs synthesized by a complex HPHT procedure.