Can you wear a cravat without a waistcoat?

It is considered poor form to wear a formal cravat without a waistcoat. An informal cravat (called a day cravat) can be worn with only a shirt. This type cravat style is tied with the cravat underneath the collar; the top button of the collar is undone; and the cravat is tucked into it.

google Day Cravats