Translation guide
In Japanese, 'light blue' is commonly expressed with specific color terms. The most standard word is 水色 (みずいろ), literally 'water color', which refers to a pale, light blue. Another common term is 空色 (そらいろ), 'sky blue', for a bright light blue like the sky. There are also more specific or nuanced terms like 淡青色 (たんせいしょく) for a very pale blue, and ライトブルー, a loanword from English. When describing objects, you can also use 薄い青 (うすいあお) meaning 'pale blue'.
The most common way to say 'light blue' as a color, suitable for everyday conversation.
The standard word for light blue. It evokes the color of water and is widely understood.
She was wearing a light blue dress.
I like this light blue wall.
Literally 'pale blue'. A descriptive phrase that can be used for any light shade of blue.
I bought a pale blue shirt.
Loanword from English. Common in fashion, design, and product descriptions.
I want light blue jeans.
Specifically referring to the color of a clear daytime sky.
Means 'sky color'. Used for a bright, clear light blue reminiscent of the sky.
A sky-blue balloon was floating in the sky.
For an extremely light, almost white blue.
水色 (みずいろ) is a general light blue, often with a slightly greenish or watery nuance. 空色 (そらいろ) is specifically the bright blue of a clear sky. In many contexts they are interchangeable, but 空色 implies a brighter, more vivid light blue.
Light blue paint and sky blue paint are slightly different.
青 by itself means 'blue', not specifically 'light blue'. To specify lightness, use 水色, 薄い青, or add 明るい (あかるい, bright) as in 明るい青 (bright blue).
Light streamed through the very pale blue curtains.