MIRA Grading system

A-D system and the A-AAA system

Top gem quality

Gem Grade Flawless pearl with excellent luster

Pearl exhibits no inclusions or imperfections prior to setting or drilling

 

A | AAA

Flawless on at least 90% of pearl's surface

Only 10% of pearl's surface may exhibit slight, concentrated imperfections

Only a single deep inclusion allowable

Luster very high to excellent*

 

A/B | AA+

Flawless on at least 80% of pearl's surface

Only 20% of pearl's surface may exhibit slight, concentrated imperfections

Only one or two deep inclusions allowable

Luster is high to very high*

 

B | AA

Flawless on at least 70% of pearl's surface

Only 30% of pearl's surface may exhibit slight, concentrated imperfections

Few inclusions allowable

Luster is medium to high

 

C | A+

Flawless on at least 40% of pearl's surface

Up to 60% of pearl's surface may exhibit slight, concentrated imperfections

Deep inclusions are limited to pearl's surface

Luster is low to medium

 

D | A

At least 60% of pearl's surface will exhibit flaws

Deep inclusions and/or white spots within inclusions on pearl's surface

Luster is poor