Gray
Gray was a color. One shade was iron gray. ()

Hair turning gray was a sign of aging. (; ; ; ) A tricky ethical area was said to have shades of gray. ()

In 2375, to hide their theft of a cloaking device, Quark and Rom pretended to be staring at a bulkhead, claiming that Rom wanted to paint his quarters the same color. Benjamin Sisko pointed out that they were already that color. Quark then reminded Rom that he had told him that very thing, to which Rom replied, "No wonder I like it. It's a very soothing shade of gray." Sisko then answered, "I'm glad you approve." ()

External link 
 
Colors