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enter image description hereFor example, a leaf in normal sunlight may be seen as green, but under a red light it is seen a red or may be dark. So the color of leaf changes according to lighting conditions. So that, does any substance possess the property, Color?

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  • $\begingroup$ What exactly are you asking? $\endgroup$
    – Anixx
    Apr 22 '14 at 6:24
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    $\begingroup$ I interpreted the question as asking whether or not color, in the colloquial sense of reflected visible light, is a fundamental property of any object as opposed to an emergent one. I'm not sure if this is correct, though. $\endgroup$ Apr 22 '14 at 8:08
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In the sense we normally use the word colour is a human perception and down to the sensors in the eye and how the brain interprets their signals. However there is an underlying physical property, and this is the reflectance spectrum or spectral reflectance curve of the material. For example, if the reflectance spectrum is strongly peaked at around 520nm it looks green when illuminated with white light. Similarly peaks at 700nm and 450nm will make the material look red and blue respectively.

The reflection spectrum is usually a result of absorption of light to excite electrons. For example chlorophyll is green because red and blue light excite electrons in the chlorophyll molecule and are absorbed in the process. Only green light is not absorbed, so the reflectance spectrum peaks in the green.

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No, the color is not a property of the substance.
It depends on the reflective properties of the substance (which is a real "property of the substance" indeed), but also on physical properties of the sample of the substance.

Silver, for example, is black in small particles, but not otherwise.
Colored crystaline substances get a lighter appearence when dgrinding the crystals I think.


The visually percieved color depends also on factors fully independent of the substance:

When we think of the actual visual color appearence, depending on the reflected light, that depends on the surrounding light.

The color we actually percieve is an interpretation of the reflected light.
That interpretation is whar we call perception. The way it works has interesting side effects like that two supstance samples reflecting very different light may still have the same visual color appearence. Also, it varies between individuals, as with color blindness.strong text

(On color perception, See Why can colors be mixed?
and Colors from a computer vs. colors from visible spectrum of sunlight )

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