I ordered Drilax Heavy Duty Diamond Hole Saw. There is no diamond coating on the tips, is this the right item that I received?

Yes, it is the right item.

 

There are two types of diamond hole saws:

  1. Electroplated: The diamond abrasive is coated over the hole saw. The diamond coating is visible but they will wear off easily with heat. That’s why these have to be used wet with constant cooling.
  2. Sintered Diamond: Here the diamond is actually within the material of the hole saw and it does not wear off. This is the professional type of tool that can be used over and over.

 

You purchased the sintered type, that is why the diamond coating is not visible.