What is lustre in gemstones and jewellery?
By Jared James · Last updated 21 May 2026
Definition
Lustre is the way a material's surface appears to reflect light, determined by the quantity of light returned and the quality and character of that reflection. In gemology it describes the surface appearance of a polished stone and is one of the key factors in identifying minerals. Different materials produce different lustres: diamonds have an adamantine lustre that is intensely bright, metals show a metallic lustre, pearls are described as having a deep pearly lustre, and some stones like jade or opal show a resinous or waxy appearance. The quality of a pearl's lustre is one of the main factors in valuing it.
Frequently asked questions
- What are the different types of lustre in gemstones?
- Gemologists use terms like adamantine for diamond-bright brilliance, vitreous for glassy stones like quartz, resinous for amber, pearly for pearl and moonstone, silky for fibrous stones like satin spar, and metallic for native metals and some metallic minerals. Each tells you something about how the stone reflects and interacts with light.
- Why is lustre important when buying pearls?
- A pearl's lustre is arguably its most important quality. High lustre means the surface is so reflective that you can almost see your own reflection in it, with a bright, sharp glow from within. Low lustre makes pearls look chalky or dull. Lustre is the first thing to look for when comparing pearl necklaces.
- Is lustre the same as shine?
- Shine is the everyday word for the same idea, but lustre is more precise. Lustre describes the character of the reflection as well as its brightness, whether it is sharp or diffuse, metallic or glassy, which tells a gemologist what mineral they are looking at and how well a stone has been polished.
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