Unlucky is a very personal thing. What I would consider an unlucky colour would be lucky for someone else. Cultures and circumstances differ widely.

As an example: Where I was raised both black and green are incredibly unlucky colours to wear to a wedding, and very nearly disastrous if worn by a member of the wedding party.

There is no such thing as an unlucky day. Although, there are unlucky things such as the devil.

unlucky

unlucky

Not lucky; not successful; unfortunate; ill-fated; unhappy; as, an unlucky man; an unlucky adventure; an unlucky throw of dice; an unlucky game., Bringing bad luck; ill-omened; inauspicious., Mischievous; as, an unlucky wag.