You can use the following for describing the colour as they are adjectives:
1. "discoloured"
2. "bruised"
3. "black-and-blue"
"bruise" is the noun --> 傷痕; 擦傷; 碰傷; 挫傷; 瘀傷
"bruise" can also be a verb--> 打傷, 撞傷
In order to describe the colour of something or maybe a body part, you need an adjective. One way to do so is to transform it to the past participle form (to make it passive or to become an adjective), which is "bruised" .
USAGE:
I picked up the apples, some of which are badly bruised.
我拾起了一些蘋果,其中一部分已經摔壞了。