When describing something's colour, would you hyphenate the words? Eg, "blood-red" versus "royal blue" [closed]

Solution 1:

You would not use hyphens when the phrase is used as a noun:

Blood red had always been his favorite color.
The flag had white lion on a field of forest green.
The dress was a fine royal blue.

Generally, I'd recommend that you use hyphens when the phrase is used as an adjective (i.e. a compound modifier):

He drank the sweet, blood-red wine.
The flag, forest-green and proud, was raised at noon.
The royal-blue dress fitted her well.

However, if the color phrase is part of a larger adjectival phrase where the color phrase itself is being modified, leave the hyphens off:

Her extravagantly royal blue dress was a sight to behold.

There may be still be some disagreement on this, though, and there are no absolute rules that apply to all possible word combinations. You are free to use whatever form you feel is most natural and easy to understand.

Solution 2:

As an add-on to the information in other answers, I would point out that color names that are made up of two colors can written with a hypen:

blue-green

NOUN A colour intermediate between blue and green; a pigment of this colour.

ADJECTIVE Of a colour intermediate between blue and green. Lexico

A colour intermediate between blue and green; a pigment of this colour.

1994 A. Theroux Primary Colors 4 The Greeks called the color kyanos (hence ‘cyan’) while the Romans would call it caeruleus, a name still used today for the artificial blue-green made from cobalt stannate.

2006 L. Eiseman Color: Messages & Meanings 78/2 By tweaking a true green to a blue green, an interesting new dimension is added. OED

Cool colors seem to recede from the eyes, which is why a dress in a blue-green looks smaller than it actually is. Linda Przybyszewski; The Lost Art of Dress

It discharged itself by a small stream into another, into which a number of large pines had been blown by a winter storm, or fallen from some other cause: in this lake its colour was blue green. Angler An; Salmonia

Some of these names may be more recent and may apply to specific points (values) in a color model (e.g., RGB or CMYK):

Wiki has entries for:

Red-violet is a deep tone of rosy magenta. Wiki

Red-purple is the color that is called Rojo-Purpura (the Spanish word for "red-purple") in the Guía de coloraciones (Guide to colorations) by Rosa Gallego and Juan Carlos Sanz, a color dictionary published in 2005 that is widely popular in the Hispanophone realm.

Although red-purple is a seldom used color name in English, in Spanish it is regarded one of the major tones of purple. Wiki

Displayed at right is the web color "orange-red". It was formulated in 1987 as one of the X11 colors, which became known as the X11 web colors after the invention of the World Wide Web in 1991.

At right is displayed the Crayola color "red-orange". It has been a Crayola color since 1930. Wiki

There are also what are known as impossible colors "that do not appear in ordinary visual functioning," but which the eye (brain) can be "tricked" into seeing. Two of those are yellow–blue and red-green. See the Wiki page for demonstrations. Wiki

We'd probably use terms like reddish orange, orangish red, and yellowish blue.