Pearls come in a variety of colors, with a delicate texture, often appearing as dense semi-transparent or opaque gemstones with a unique pearly luster. The intensity of this luster varies depending on the thickness and transparency of the nacre, ranging from weak to strong pearly luster. Saltwater pearls and freshwater pearls differ in luster, shape, and other characteristics.
Under long-wave and short-wave ultraviolet light, pearls may exhibit a pale blue-white, light blue, light yellow, or pink fluorescence, though some pearls show no fluorescence.
Under X-ray exposure, pearls may exhibit yellow-white and green phosphorescence.
Pearls have high toughness, especially non-nucleated pearls, and higher-quality pearls are more difficult to crush.
When bitten, pearls have a characteristic gritty texture.
A round pearl dropped freely from a height of 1 meter onto a glass surface can bounce up to 20–40 cm.
Pearls have low chemical stability, making them sensitive to acids, alkalis, and heat.
Pearls are soluble in acetone, benzene, carbon disulfide, and various acid solutions. When dissolved in acid, they release CO₂ gas and leave behind fibrous organic residues.
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