YOU SAID:

it becomes either gray, or a darker shade of an existing color

INTO JAPANESE

灰色、または既存の色の暗い色合いになります

BACK INTO ENGLISH

Will be a dark shade of gray or an existing color

INTO JAPANESE

濃いグレーまたは既存の色になります

BACK INTO ENGLISH

Will be dark gray or existing color

INTO JAPANESE

ダークグレーまたは既存の色になります

BACK INTO ENGLISH

Will be dark gray or existing color