Vapour phase deposition is divided into two main categories: Chemical Vapour Deposition (CVD) and Physical Vapour Deposition (PVD). Both technologies are similar and are further subdivided into subcategories. The principle involves placing the piece to be treated (substrate) in a vacuum reaction chamber. The substrate is heated (between 700°C and 1000°C for CVD, and between 200°C and 450°C for PVD). One or more elements (precursors) are then introduced in a gaseous state into the reaction chamber. The precursors can be of different types: silicon, carbon, tungsten, gold, etc.

In the case of CVD treatments, a chemical reaction occurs between the substrate and the precursors, which chemically fuse, ensuring excellent adhesion of the treatment. For PVD treatments, the precursor layers are physically deposited on the surface of the substrate by condensation. While CVD provides better adhesion, the high temperatures it requires limit its use.

Depending on the chosen precursors, vapour phase deposition can protect the substrate from corrosion, harden its surface, modify its coefficient of friction, or change its electrical conductivity.

The range of applicable colours is much broader than those offered by other surface treatments and continues to expand. The applications in watchmaking are extensive, with vapour phase deposition treatments used for the casing, movement, and tooling. The process can have various names depending on the precursors and the chosen method. For instance, DLC (Diamond-Like Carbon) is used for a PVD treatment where the main precursor is amorphous carbon, valued for its hardness.