These are corks with top quality visual appearance - excellent surfaces, with no major visual flaws and few small ones.

• No holes or pores which exceed 2mm.
• No cracks originating at the ends which exceed 11% of cork length.
• No cracks in the body of the cork to exceed 18% of cork length.
• All cracks must be tight and not open.
  No horizontal cracks.
• No worm holes, hardwood, belly spots, or greenwood.
• Several narrow and shallow lenticels are acceptable if they are free of dust and particles.
  

Grade B

These are corks of good visual appearance with no major visual flaws and with surface visual flaws of no depth or substance.

• No holes or pores which exceed 5mm.
• No cracks originating at the ends which exceed 18% of cork length.
• No cracks in the body of the cork to exceed 25% of cork length.
• All cracks must be tight and not open.
• Lenticels and horizontal cracks must not open up when ends of the corks are bent.
• No Greenwood. No angeled or deformed corks.
• Very small chips and lateral worm activity in the middle of the body of the cork may be acceptable.
• Lenticels at ends must not be wide or deep and should be free of dust and particles

Grade C

These are corks of average visual appearance with one or more major visual flaws which will be of cosmetic nature only. Thus they may be aesthetically unappealing, but functional.

• No cracks, channels, hardwood or belly spots which exceed 55% of cork length.
• Lenticels and horizontal cracks on body may open up when ends of the corks are bent.
• Greenwood to 55% of cork length is acceptable unless severe depth or width.
• Large chips are acceptable.
• No worm activity from end to side which exceed 55% of cork length.
• No dry years which exceed 55% of cork length.
• There may be heavy, but not continuous porosity.