CCD inner tubes are coated with PVD (Physical Vapor Deposition).
Fading can be caused by shock absorber operation friction, environmental dust, dirt, air salinity, and contact with chemicals. High mileage without changing the fork oil can also accelerate wear. Surface fading does not affect sealing but oil seal installation damage can cause the seal spring to contact the inner tube directly, leading to PVD fading or even chromium plating damage.