Natural and Lab Grown diamonds can be colored by Irradiating them with High Energy Electron Beam.
Nitrogen-vacancy centers are typically produced from single substitutional nitrogen centers by irradiation followed by annealing at temperatures above 700 °C.
Irradiation produces lattice vacancies, which are a part of NV centers.
Those vacancies are immobile at room temperature, and annealing is required to move them. S
ingle substitutional nitrogen produces strain in the diamond lattice; it therefore efficiently captures moving vacancies, producing the NV centers.
Read more on Wikipedia...
High Temperature Annealing of the Diamonds under Extremenly High Pressure to reduce plastic deformity to improve transperency and color grade
Turnkey consultation and solutions for setting up a lab for Diamond Synthesis using CVD reactor systems and peripherals like gas generators, water chillers, vacuum pumps, gas connections, laser cutters, etc.
Coring, Seeding and Shaping of Lab Grown Diamonds