Grade 1 Sapphire
Inclusions, lineage, bubbles and twins are not permitted.
Grade 2 Sapphire
Inclusions, lineage and twins are not permitted. Micro bubbles with a diameter of 10 microns or less are permitted. (Bubbles less than 10 microns are generally not visible with the naked eye).
Grade 3 Sapphire
Inclusions, lineage and twins are not permitted. Uniformly distributed bubbles not larger than 50 microns in diameter and not closer in distance between bubbles than 500 microns are permitted.