A quiet revolution in industry has happened over the last 50 or so years due to the use of diamond and cubic boron nitride (CBN) in many applications. Joining of diamonds to various materials via brazing is very specific compared with conventional brazing due to the unique nature of diamond. This chapter describes the properties of diamond and CBN, and their wetting by and interaction with metals and alloys; factors that affect these interactions; and practical aspects of diamonds and CBN joining. Some properties of brazed joints of diamond and CBN with different metals, as well as cemented carbide inserts, are presented and discussed. Finally, application examples are provided.