As pearl diameter size is considered one of the primary factors contributing to overall pearl value, slight increases or decreases in pearl diameter often dramatically impact the overall cost of the jewelry piece.

This is particularly true with pearls that are harvested from small mollusks/oysters such as the Akoya pearl, which is harvested from the world’s smallest pearl producing mollusk (Pinctada Fucata martensii).

Pearl size guides below. Figure 1 shows the size of pearls from 6.5mm to 9.5mm in 1/2mm increments. Figure 2 shows the size of pearls from 6mm to 13mm in 1mm increments. Size of the pearls is compared to a U.S. dime, which measures 17.91mm in diameter. Click for larger images.

Akoya Pearls: Akoya Saltwater Pearls are most commonly available in sizes from 5.5mm to 7.5mm. Akoya pearls can be as large as 10mm, but sizes that large are very rare and costly.

The most popular size for Akoya Saltwater Pearls is 7.0-7.5mm, which are suitable for dress, casual and business attire. The second most popular size, likely for their affordable price is 6.5-7.0mm. Those with a larger budget and a taste for bigger pearls often chose 7.5-8.0mm and 8.0-8.5mm pearls. We also offer 8.5-9.0mm and 9.0-9.5mm Akoya Pearls for those who really want to make a statement.

Freshwater Pearls: Freshwater pearls are available in a very wide range of sizes, from 2mm "micro" pearls to more than 10mm in diameter. The most popular size in our experience has been between 7 and 9mm. Freshwater pearls are also more affordable than any other pearl type because of large supplies. Do not let this form your opinion on their value, however, as Freshwater pearls are very beautiful and in some cases rival Saltwater pearls for luster and overall appearance.

Tahitian & South Sea Pearls: These pearls are famous for their large sizes. They are also very costly due to their rarity and because of the difficult culturing process.