The Order of Merlin (abbreviated O.M.) was a British award bestowed upon witches and wizards who had achieved great things for the Wizarding World. It had three different levels: First Class, Second Class, and Third Class.
Appearance and classes
The Order of Merlin consisted of a golden medal which hung on a coloured ribbon indicating its class. There were three different classes of Order of Merlin that were awarded:
First Class: Awarded for "acts of outstanding bravery or distinction" in magic. The colour of the ribbon for this class was green, which was believed to represent Merlin's Hogwarts house, Slytherin.
Second Class: Awarded for "achievement or endeavour beyond the ordinary." The colour of the ribbon for this class was purple.
Third Class: Awarded to individuals who "have made a contribution to our store of knowledge or entertainment." The colour of the ribbon for this class was white.