We know that the larger the size, the higher the price. But price jumps between pearl sizes are often uneven. As the size reach the 8 - 9mm or above, pearl prices tend to increase much higher.

According to CIBJO (The world Jewelry Confederation) The Pearl Book, different pearls are measured by different methods with different minimum units’ expression.

Pearl size measuring methods:

 Pearl Size Description
 Single Pearl
Round shape: average diameter
Fancy shape: maximum diameter, maximum length

Pearl size: <10mm, expressed to the nearest 0.25mm
                 >,=10mm, expressed to the nearest 0.1mm

 Graduated Strands
Maximum diameter of the largest pearl and the smallest pearl on the strand

Pearl size:expressed to the nearest 0.1mm
e.g.8.6-13.3mm

 Uniform strand
Stated as the minimum size

Pearl size:expressed to one half(0.5)mm variations
e.g. 7.0-7.5mm