Zircon is somewhat soft so avoid scratches and sharp blows. Avoid hot water and household chemicals. Brown Zicon is usually heat treated to change them to colorless or blue Zircon. Blue stones that revert to brown will regain the blue if reheated. Blue Zircon reheated in the presence of oxygen will change to a golden yellow. Zircon will have more wear on its facets than diamond. Zircon is imitated by colorless glass and synthetic spinel.
Click on the gem name for more information about that stone.