There are three methods to weld diamond segments onto the saw blade core:

Silver/copper brazed diamond blade: 

Diamond segments are brazed to the steel saw blade core by using a silver solder. High frequency welded diamond saw blade is that after melting of silver solder or copper solder between the base of high-frequency diamond saw blade and diamond segments, the two are connected together by inductively heating by high-frequency welding machine.  Silver brazed diamond blade can only be used in wet cuttings. If they are used in dry cuttings, the silver solder may melt under the high temperature generated in the dry cutting and the segments can break from the steel core and be extremely dangerous. People use high frequencey machine or fire to weld them on blade blank.

Wholly sintered diamond blade:

The diamond blade is made by putting the steel core together with the diamonds and the metal bond materials(metal powder) into a mold and then sintering them in a sintering machine.

Laser welded diamond blade:

The laser melt the diamond segment and the steel core creating a stronger welding, which can hold the diamond segments even in high temperatures, so laser welded diamond blades can be used to cut many types of materials without water cooling.