Pearl criteria continued

Tahitian black pearls that have been nucleated typically range in size from 7 to 18mm in diameter. Larger pearls exist but anything beyond 16mm is extremely rare. Quality is broken down into A, B, C and D categories. Another system of grading exists that is defined by A through AAA. Both systems are valid but both also have degrees of subjectivity depending on the seller. Honest sellers understand the long-term benefits of proper grading.