American Pearl · Pearl Guide

A Brief History of Pearls: Quality Factor One: Luster

The short answer

Luster is the most important pearl quality factor. It combines brilliance, how sharply the surface reflects light, with the inner glow that comes from light passing through the nacre. High-luster pearls look bright and reflect nearby objects clearly; low-luster pearls look dull, chalky or flat white, usually because their nacre is thin.

Reviewed by American Pearl’s pearl specialists · Updated October 2026

	A brief history of pearls		QUALITY FACTOR ONE: LUSTER When experts evaluate pearls, luster is the most important quality. It refers to two things: its brilliance, which is the way its surface reflects light, and its inner glow, which is the way it refracts light. The Pearl Luster Scale Typically, experts evaluate a pearl's luster on a scale that ranges between high and low. Pearls with a high luster are bright and have a deep glow. High-luster pearls can reflect nearby objects clearly, and most - but not all - have a thick nacre coating. However, thick nacre doesn't guarantee a high-luster pearl; that's because some oysters have genetic imperfections that don't allow them to secrete nacre in perfect patterns. Pearls with low luster may appear dull, chalky or too white. Usually, pearls with low luster have thin nacre. Dividing pearls by quality factors, including luster, is not an easy task. In fact, pearls are first sorted into broad categories to make the sorting process easier. Each time a pearl goes through the sorting process, it is further classified until it is properly classified.
	How pearls form in oysters
	How pearls are harvested
	How pearls brought to market

	Know your Akoya pearls
	Akoya Pearl Cultivation
	Akoya Pearl Harvesting
	Akoya Pearl Processing
	Akoya Pearl Evaluation

	Quality Factor One: Luster
	Luster of Akoya Pearls
	Quality Factor Two: Surface
	Surface of Akoya Pearls
	Quality Factor Three: Shape
	Shape of Akoya Pearls
	Quality Factor Four: Color
	Color of Akoya Pearls
	Quality Factor Five: Size
	Size of Akoya Pearls

	Know your South Sea pearls
	South Sea Pearl Cultivation
	South Sea Pearl Harvesting
	South Sea Pearl Processing
	South Sea Pearl Quality Evaluation
	Luster of South Sea Pearls
	Surface of South Sea Pearls
	Shape of South Sea Pearls
	Color of South Sea Pearls
	Size of South Sea Pearls

	Know your Tahitian pearls
	Tahitian Pearl Cultivation
	Tahitian Pearl Harvesting
	Tahitian Pearl Processing
	Tahitian Pearl Quality Evaluation
	Luster of Tahitian Pearls
	Surface of Tahitian Pearls
	Shape of Tahitian Pearls
	Color of Tahitian Pearls
	Size of Tahitian Pearls

	Gift Giving Occasions


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Pearl luster: common questions

What is pearl luster?

Luster is the way a pearl’s surface reflects light (brilliance) together with the way light passing through the nacre gives it an inner glow.

How do I tell if a pearl has good luster?

To tell if a pearl has good luster, look for your reflection. A high-luster pearl mirrors nearby objects with crisp edges. A low-luster pearl looks chalky, cloudy or flat white.

Does thick nacre always mean high luster?

No, thick nacre does not always mean high luster. Most high-luster pearls have thick nacre, but some oysters lay nacre down unevenly, so a thick-nacre pearl can still have only fair luster.