| Visual Criteria |
| Feature | Description | Tolerance |
| Blemish | Stained or discolored area associated with normal processing | 1.5mm (.06") Max. |
| Chip | Open: Material removal along an edge. Closed: Damaged area along an edge where material is still in place. | 1.5mm
(.06") width across face by 1.5mm (.06") deep into face by unlimited
length along edge. |
| Crack | Fracture line without separation visible to the naked eye | None allowed |
| Foreign Material | Particles adhering to surfaces | None allowed |
| Holes/Pits | Voids in surfaces | 1.5mm (.06") Max in any direction |
| Inclusion | Foreign
material embedded in ceramic body or a stain not associated with normal
processing | 1.5mm (.06") Max in any direction |
| Porous Area | Area that retains dye and upon sectioning shows evidence of dye penetration | None allowed |
| Surface Marks | Scratches, grind marks or other long shallow grooves cut into a surface | Not exceeding dimensional limits of a feature |