look-see whether the color and design are in line with your preferences, and whether the lines and patterns are natural and comfortable. If you can take down the brick, you can observe whether the flatness of the brick is straight with one eye facing the corner. If it is polished, you can stick the polished faces of two bricks together, and closely check whether there is a big gap on the edge (the deformed brick faces are not jointed)
listen-tap the ceramic tile surface with a hard object, and listen with your ears. The crisp sound indicates that the sintering degree is good, and the ceramic is fired at about 12 degrees. If the tapping sound is dull, it indicates that the sintering degree is not good enough, or there are problems such as dark cracks and interlayer.
Touch-close your eyes and put your hand on the surface of the brick, gently touch it, and feel the texture of the brick surface carefully. A good brick will give you an illusion. For example, if it is a glazed tile with imitation leather, you will feel the real leather when you touch it. If it is a polished tile, it will feel very smooth, and if it is polished, it will feel slippery.
try-turn the brick upside down, and drop 2-5 drops of water on the top of the bottom of the brick (if the size is large, drop more drops) to see if it can flow from the previous direct current to the bottom. If it flows to the bottom quickly, it means that the water absorption of the brick is low and the quality of the brick is good. If it disappears halfway, it means that the water absorption is too high, and the quality of the brick is not good enough, which is easy to cause problems after paving. If it is a polished brick, you can use an oily big-headed pen to point a point on the brick surface and gently wipe it off. The shallower the trace, the better the antifouling ability. Generally, the brick with antifouling wax can be rubbed hard without leaving a mark. If it is super clean and bright, it can be wiped gently without leaving a trace.
The above is summarized by my experience as a professional ceramic technician (please note that I am not a salesman or something like that) for your reference. If you don't understand or find anything wrong, please leave a message on my Baidu.
additional note: the internal quality of polishing mainly depends on the water absorption rate, which is required to be below .5 in the national standard, but the water absorption rate of real brand manufacturers is controlled below .2, and the external quality mainly depends on two indicators: deformation (within .5) and gloss (greater than 6, the higher the better). These indicators are the most important indicators controlled by brand manufacturers, which can only be measured with special equipment, while consumers can consult with merchants to see what their product indicators are, and then compare several merchants to see who is more cost-effective, for reference.