Physical Properties
The unique luster of pearls depends upon the reflection, refraction, and diffraction of light from the translucent layers. The thinner and more numerous the layers in the pearl, the finer the luster. The iridescence that pearls display is caused by the overlapping of successive layers, which breaks up light falling on the surface. In addition, pearls (especially cultured freshwater pearls) can be dyed yellow, green, blue, brown, pink, purple, or black. The very best pearls have a metallic mirror-like luster.
Because pearls are made primarily of calcium carbonate, they can be dissolved in vinegar. Calcium carbonate is susceptible to even a weak acid solution because the crystals of calcium carbonate react with the acetic acid in the vinegar to form calcium acetate and carbon dioxide.
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Famous quotes containing the words physical and/or properties:
“The real stumbling-block of totalitarian régimes is not the spiritual need of men for freedom of thought; it is men’s inability to stand the physical and nervous strain of a permanent state of excitement, except during a few years of their youth.”
—Simone Weil (1909–1943)
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—John Locke (1632–1704)