The differene between Rectified and non Rectified Tiles.
A mechanical process straightens the tile edges and ensures they are perfectly square. So all the tiles are exactly the same size and therefore be laid with a minimal grout joint of 1.5mm. Non - rectified tiles on the other hand are tiles with a natural uneven edges that require a wider grout joint. Non - rectified tiles usually have a slightly rounded, beveled or hand made edge.