The specifications of vitrified tiles are following. 
• The tiles are of approved make and are generally confirmed to ISI 777
• They are flat and true to shape and free from blisters crazing, chips, welts, crawling or other imperfection, detracting from their appearance.
• The tiles are square or rectangular.
• The thickness of the tiles is 5 mm to 7mm.
• The top surface of tiles is glazed which is either glossy or matt finish.
• The under side of tiles should not have glaze on more than 5 % of the area.
• The edges of tiles should preferably be free from glaze. However any glaze if unavoidable should be permissible only up to 50% of surface area of the edge. These tiles are available in different colors and designs.

Thanks