The Order of St Michael and St George is awarded to men and women of high office, or who render extraordinary or important non-military service in a foreign country.
It can also be conferred for important or loyal service in relation to foreign and Commonwealth affairs.
There are three classes within the Order in descending seniority:
Knight Grand Cross or Dame Grand Cross (GCMG)
Knight Commander (KCMG) or Dame Commander (DCMG)
Companion (CMG)
Source: The official website of the Monarchy