What is a 'blemish' in a diamond?

What is a 'blemish' in a diamond?

John Cordova (Vice President of Human Resources, Robbins Bros.) gives expert video advice on: What does a diamond's 'carat weight' mean?; What does a diamond's 'clarity' mean?; What is the diamond clarity grading system? and more...

A 'blemish' in a diamond is actually a marking on the surface of the diamond that can be seen either with, or without, magnification.