Pearl Nacre Thickness (Maki)

Nacre Thickness

“Maki” refers to the thickness of the nacre.

Judging nacre thickness with the naked eye requires long experience, and it is difficult for ordinary customers to identify it accurately in a store.

Generally, the thicker a pearl’s nacre, the less it tends to change over time, and the longer its beauty tends to last.

Nacre thickness is also a very important factor in identifying a fine pearl. A pearl with thick nacre that is also translucent produces a beautiful pearly luster with depth.

About Pearl Nacre Thickness

The thickness of the nacre in a pearl is called “maki-atsu” (nacre thickness).

Nacre thickness is one of the most important factors in choosing a pearl. Because nacre thickness is directly linked to luster and the degree of change over time, Tensei Pearl pays particular attention to it in our cultivation.

Comparing Nacre Thickness

Nacre is formed by thousands of layers of calcium carbonate crystals about 0.4μm (microns) thick and a protein called “conchiolin” building up on top of one another.

Even pearls cultivated for 1 year, called “tonenmono,” can sometimes have thick nacre.

On the other hand, pearls cultivated for 2 years, called “koshimono,” have a higher chance of developing thick nacre because of their longer cultivation period.

How Nacre Thickness Changes Luster

The thicker a pearl’s nacre, the more complex the reflection of light from within becomes, and a luster with depth appears on the surface.

Comparing the surfaces in the photo with the cross-section diagrams, you can see that the thicker the nacre, the more the center of the pearl seems to stand out.

Even if the finished pearls are the same size, if the nuclei inside differ in size, their nacre thickness and quality will also differ.

Although it depends on the size of the pearl, a nacre thickness of about 0.4mm to 0.6mm on one side can be considered standard.

Among large pearls, there are rarely pearls with a nacre thickness of 1mm or more.

Nacre Thickness and Change Over Time

Because pearls contain organic matter, change over time always occurs.

Even when there is no visible change, the pearl gradually changes in its composition.

It is generally said that the thicker the nacre, the less a pearl changes over time. However, as long as the nacre is above a certain thickness, discoloration will not be accelerated by the nacre being thin.

On the other hand, with pearls whose nacre is extremely thin — for example, a nacre thickness of 0.2mm or less — the nucleus may show through, or the surface nacre may peel off.

Nacre Thickness and Luster

People tend to think that “the thicker the nacre, the better the luster, without exception,” but a pearl’s beauty is not determined by nacre thickness alone.

What matters is the quality of the nacre itself.

If the nacre is uneven or cloudy, no matter how thick it is, light will not reflect cleanly, and beautiful interference colors are less likely to appear.

Therefore, a good pearl is not simply one with thick nacre, but one in which translucent, high-quality nacre has formed solidly and thickly.