Does 色 (iro) have to be placed after colour kanji?


For example:

English: This juice is purple.

日本語 1: このジュースは紫です。

日本語 2: このジュースは紫色です。

Does the kanji 色 need to be palced after colours?

From what I understand, sometimes the kanji 色 is necessary. For example, in
灰色, without the 色 kanji, it would just mean "ash", right? But, I don't get why
紫 needs to have 色 next to it.




You don't need it because when you reply it, you have usually been talking
about color. Even without that condition, you don't particularly need it,
after all.




You don't need it because when you reply it, you have usually been talking
about color. Even without that condition, you don't particularly need it,
after all.

