18MM is considered to be the best quartz stone thickness for Indian Kitchen Countertops. Because Kitchen Manufacturer makes kitchen by considering 18MM as the thickness of Countertop. Secondly, a protection board of 18MM is placed over the cabinet on which the countertop will be installed is also of 18MM. If thickness will be 20MM, the stone installer will put 2MM packing between board and stone that make the stone hollow and has chances to broke. 15MM thickness has chances to broke due to low thickness and creates bad impression of front molding look. Customers are pushed to by 20MM due to unavailability of 18MM thickness in other brands.