Case
Thermally blued titanium
High confidenceTitanium coloured by controlled heating, so the blue is an oxide layer grown in the surface of the metal rather than a coating applied to it. Used for cases, dials and components.
Part reference
- Brand
- De Bethune
- Material
- Titanium with a heat-grown oxide layer
Documented variations
Classification
FactoryDocumented as shipped from the factory for this reference and period.PeriodNot original to this watch, but correct for its production period.ServiceFitted by the manufacturer's own service network. Not a defect.AftermarketThird-party part. Affects originality, not authenticity.ModifiedGenuine parts in a configuration the factory did not sell. Affects originality and value, not authenticity.CounterfeitDeceptive reproduction intended to pass as genuine.UnknownEvidence on file does not settle the question.Thermal blue with depth and surface variation
FactoryProbableWhole production
Colour that has depth, varies slightly across the surface, and follows the topography rather than levelling it. At an edge it cannot chip to reveal a different colour, because there is nothing beneath it but the same metal.
Painted, lacquered or PVD blue
CounterfeitProbableWhole production
Sits on top of the surface, is uniform, levels the topography beneath it, and can chip or wear at an edge to expose a differently coloured substrate. The edge behaviour is the decisive test and requires only a loupe.
Documented on these references
- De Bethune DB28Factory
Whole production
Provenance of this record
Sources & Evidence
De Bethune — collection and technical documentation
De Bethune SA
- Accessed
- 2026-08-19
Cited for
Last verified: Not yet reviewed