Hyphens, En Dashes, Em Dashes
Q. Please help. Does “blue black berries” require a hyphen? What about “deep violet blue color”? We’ve had to look beyond CMOS for guidance because the issue of compound color modifiers isn’t thoroughly covered, although as CMOS is our primary reference, we would happily defer to you. Many of our publications include compound color modifiers, and it’s become a bit tense around here as some insert hyphens and others remove them.
A. You’re right—so CMOS clarified this issue, starting with the sixteenth edition. Simply hyphenate compound color modifiers before a noun but not after. See the table at CMOS 7.89, section 1, under “colors.”