Pearl Qualities
Overall, the important characteristics of pearls are:
- shape
- size
- color
- surface
- nacre quality
- luster
In general, the larger and rounder the pearl, the more valuable—with the exception of some larger and unusual baroque pearls.
Some colors are rarer than others, too, such as true peacock and golden hues among South Sea pearls and natural colors of pink, lavender, and peach freshwater pearls, which increases their worth.
Smooth, clean surfaces are the ideal in all pearls, though sometimes rare colors can command a premium even if the pearl surface isn’t perfect.
Nacre quality refers to thickness—more is considered better
and luster; the more intense the luster, the more valuable the pearl.
Freshwater pearls largely have the lowest luster, though metallic surfaces do occur and are more valuable.
Akoya pearls are known for their luster, while their sizes typically don’t exceed 10 mm, though baby Akoya pearls have grown popular in recent years and offer another type of entry product for their smaller sizes, abundance, and because they require less growing time.
South Sea pearls are known for their thick nacre (because they grow faster in warmer waters), luxurious luster, and large sizes—with some exceeding 20 mm
Similar to the 4 C’s of diamond buying, familiarize yourself with the Five Virtues related to pearl purchases.
Luster
For cultured pearl experts, luster is most important when determining pearl quality.
Luster derives from the pearl’s countless layers of pearl nacre, the natural substance that forms the pearl itself.
Luster describes the beauty you see as light travels through the nacre of the pearl.
It is the nacre that causes light to refract from the pearl’s layers, giving each pearl its unique milky appearance.
Complexion
Surface complexion refers to the physical blemishes or marks on the pearl’s surface.
When evaluating complexion, the trade uses terms such as blemish, spotting, and cleanliness.
Since cultured pearls are grown by live oysters in a natural environment, there are many uncontrollable forces that affect their surface.
Color
The desirability of different pearl colors rests in the eye of the beholder.
The most popular color is white or white with slight overtones.
Pearls that are naturally colored, rather than color enhanced by artificial means, will add value to the pearl.
Shape
Classic shapes range in descending order of value from round to near-round, and from oval to drop.
It’s important to understand that in pearl industry terms, the shapes from round to drop are pretty symmetrical, while anything baroque denotes a pearl that is completely asymmetrical or freeform.
Size
Cultured pearls are measured by their diameter in millimeters.
They can be smaller than one millimeter in the case of tiny seed pearls or as large as twenty millimeters for a mature South Sea pearl.
Generally speaking, the larger the pearl, the more valuable it will be.
How do Pearls Form Their Shape?
To help better understand how a pearl takes its shape, we must first briefly explain how pearls are made.
A pearl begins to form when a foreign substance, or an irritant, makes its way inside of a mollusk.
This irritant essentially acts as the pearl’s nucleus.
To protect itself, the mollusk begins to coat the irritant with layer upon layer of nacre, the main substance in pearls, and a pearl slowly begins to develop.
One critical aspect regarding the pearl’s shape is the shape of the nucleus that the mollusk coats with layers of nacre.
For cultured pearls, spherical beads are typically used as the nucleus for a perfectly round pearl.
As the pearl begins to slowly form with each layer of nacre, micro-terraces form around it.
Water molecules bounce off these terraces and create energy.
As a result, causing the pearl to slowly begin to rotate and enhance the pearl’s spherical shape.
Shapes such as semi-round, drop, and baroque are often the result of mantle-tissue being used for the nucleus instead of a spherical bead.