There are a number of things that affect the perceived colour of an object.
- the actual colour (local colour) of the object
- the colour of the light shining on it
- the colour of anything near or next to the object, including the world/background colour
- highlight and shadow areas
- angle to the source light (main light) and viewer
- reflections and specular highlights
- Ambient light
- lots more that don’t immediately come to mind…
In your case, the first thing I’d do is change your world colour from Blender’s default “Hideous Blue”. Make it white or off white if you want to assess the object colour better. Almost any colour next to that strong blue is going to be “off” - except maybe a bright yellow which would actually increase in intensity.
Make sure your source light is pure white (All RGB sliders at 1.000) and energy is turned up high enough (this is arbitrary and depends on distance, among other things).
Check too if you have a value set for Ambient light in your world material settings. If so, this will also affect your object colour since the Amb slider is set to 0.500 in the Shaders panel (it has no effect if AmbR/G/B is set to 0,0,0)