What's the difference between sintered and electroplated or coated diamonds?

Electroplated, or coated diamonds are bonded to the drill bit using nickel in a single layer and although won't last as long as sintered they are a cheaper alternative. With Sintered, the diamond has been bonded to the matrix at very high temperatures and therefore has several layers of diamonds which by dressing or cleaning with an aluminium oxide stone will help maintain the life of your bur or wheel revealing a new layer of diamonds each time.