This is one of the most beautiful and unique effects found on a pearl, and the hardest one to explain. This effect is given -in part- by the pearl's nacre thickness, its nacre's spiraled suture lines, its deep luster, surface purity and color, so it is caused by the reflection, the refraction, the interference and diffraction of light upon a pearl. It can be more easily explained as an Iridescence on its surface, allowing the pearl to display subtle color variations as you move it. The more intense the effect is the more desireable the pearl is.

The effect known as orient gets its name from ancient times. The pearls of the Persian Gulf where known as "Oriental Pearls" to the Romans, and thus the name "orient" was tagged to pearls that possessed a unique play of colors on their surface. Ancient Romans obtained pearls from many sources, but most of them came from rivers and lakes in Europe (Scotland, France and Germany), those freshwater pearls rarely had the beautiful orient that saltwater pearls have. Orient is then, a characteristic more common to saltwater pearls.

When this optical  effect manifests itself as a deep "halo effect" (mostly in the colors pink/violet and green/blue), the pearl may display as a series of concentric rings (with the color gradually changing to another one) that go from the pearl's diameter and into the center. A pearl with such an effect will never be mistaken as a fake-pearl and it is highly coveted. This effect was once refered to as the "fish eye" effect and is now usually refered to as "overtones". Pearls that were able of displaying it were highly valued.

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El oriente de una perla es un juego de color en la superficie que es inimitable. Es un efecto óptico que únicamente se utiliza exclusivamente para referirse a las perlas por lo que es altamente deseable que se presente en ellas en cualquiera de sus variantes: oriente, sobretono e iridiscencia.

En las mejores perlas el oriente se observa un segundo (incluso un tercer) color o sobretono. Esto es difícil de describir pero básicamente es como si existiesen "aros" de colores en la perla. En ocasiones se refieren a este efecto concéntrico como “efecto ojo de pescado”.

En perlas de superficie ligeramente amartillada el efecto cambia y se observa como iridiscencia en la perla: leves destellos de diferentes colores que se observan en la perla conforme se le va girando.

El oriente no se presenta en todas las perlas –mucho menos en las de baja calidad- y se puede perder en perlas maltratadas (incluyendo aquellas que han sido teñidas, blanqueadas y pulidas).