Efflorescence / White hazing or Cement and Grout damage?

WHAT CAN CAUSE DISCOLOURATION AND WHITE HAZING?

Moisture and polymer from adhesive used to complete installations can be drawn up through the natural capillaries within the stone. This can release minerals and salts from within the stone, causing a light bloom or white haze from within. In this instance, there is no chemical cure or cleaner that will remove the stains from the stone.

It is also common to see grout floated across the surface (in order to complete grouting between the tiles). This will often fill some of the open capillaries contributing towards a mottled and uneven appearance. In this case, grout on the surface can be removed using a chemical cleaner but grout that has settled within the open pores is likely to be impossible to remove. No amount of scrubbing or cleaning will make any difference. In both cases any additional sealing would only further highlight the marks left by the adhesive and the grout.

REMOVING THE DISCOLOURATION AND HAZING
There are two alternative approaches to addressing this issue:

For surface grout stains attempt to clean back the surface of the tile with a specialist intensive cleaner and reseal. 
Remove and replace the tiles.

Efflorescence

After I sealed my floor, the grout and stone turned white in areas. What caused this?

This may be a case of efflorescence. Efflorescence is a white powdery substance that is produced when cement or masonry material such as grout, concrete substrates, and/or cement adhesives become wet. This can occur either in the installation process or after a heavy-duty cleaning and rinsing process. Sealing the surface prior to moisture evaporation may cause efflorescence to appear. Locked-in moisture will usually wick salts and alkali substances up through the stone’s capillaries to its surface. After the moisture evaporates, the white powdery substance presents itself. There are a couple of ways to remove the efflorescence. On surfaces that are not acid-sensitive such as granite, slate, ceramic tile, sandstone, clay tile, etc., use Extreme cleaner to clean the efflorescence away. For acid-sensitive materials such as marble, limestone, travertine, onyx, or masonry, you can abrade the efflorescence away using Pre sealer cleaner and an abrasive nylon pad. In each case, we recommend that you seal the surface again after the removal process is complete and the surface is completely dry.