The corners of the tiles must be a 90 degree right angle, unfilled corners on front surface is not allowed. Four sides of the bottom surface have corner crack is acceptable if not affecting the paving.

Above 90 degrees, matte surface: 20-30 degrees;

No obvious cracks. Penetrating cracks are not acceptable; if touching tiles couldn't feel this crack, and slight inconspicuous cracks (no more than 3cm in length), will be allowed.

Standard: 1cm, within minus 0.5mm is acceptable , do not accept positive excess.

The diameter is less than 3mm, one surface do not exceed 3 holes;

Dark spots and crystal spots' diameter are not allowed to exceed 2cm; obvious erythema and water lines are not acceptable, light erythema, macula is not obvious and naturally forms a transition, partial acceptable; white line , Gold lines and dark spots, according to customer standards.