The word for “color” is 色　いろ(iro).

Black 黒　くろ (kuro)

Blue 青　あお (ao)

Red 赤　あか (aka)

Green 緑色　みどりいろ (midori)

Sky Blue 水色 みずいろ (mizuiro)

Brown　茶色　ちゃいろ (chairo)

White 白 しろ (shiro)

Pink 桃色　ももいろ or ピンク (pink)

Purple 紫　むらさき (murasaki)

Yellow 黄色　きいろ (kiiro)

Orange オレンジ色 (orenji iro)

Grey 灰色　はいいろ (haiiro)

Gold 金色　きんいろ (kiniro)

Silver 銀色　ぎんいろ (giniro)

So basically if you want to know someone’s favourite color, you can ask:

好きな色は何ですか(Suki na iro wa nan desu ka)

You can answer that question simply with the color: 赤です (aka desu) – It’s red

You can also say: 好きな色は赤です (suki na iro wa aka desu) – My favourite color is red.

If you want to know what color something is, you can ask:

何色ですか (Nani iro desu ka) – 赤です (aka desu) It’s red.

Interesting facts:

→ 青 (ao) can mean either “blue” or “green”. Japanese people often use 青 in cases where Western people would use “green”. The best example are the traffic signals: the green lights are 青 信号 (ao shingou). Another example are green fruits and vegetables like green apples, they are also referred to as 青りんご (ao ringo).

 

By adding the prefix 真 まっ (ma) you can emphasize the color:

真赤　まっか (makka) – bright red

真黒　まっくろ (makkuro) – jed black

真白　まっしろ (masshiro) – pure white

The suffix っぽい (-ppoi), which means “-ish”, can be used when you don’t know exactly what to call a color.

Example: 真央はどの人ですか。ー　緑っぽい靴を履いている人です。

Mao wa dono hito desu ka? – Midorippoi kutsu wo haiteiru hito desu.

Who is Mao? – She is the person who wears the greenish shoes.

To learns the pronunciation of each color take a look at the video: