Why do people bite pearls to see if they're real?

Question

How do you know if they are when you bite them?

Answer 1

The Tooth Test
What you are describing is called the “tooth test”. The tooth test is a good way to determine whether a pearl is genuine or fake. The test is performed by gently rubbing the pearl over the biting edge of the upper front teeth. A genuine pearl will feel gritty like very fine sandpaper, and a fake should feel perfectly smooth.

What Are You Feeling?
A pearl is composed of calcium carbonate which is laid down in polymorph platelets of aragonite. These platelets are laid one on top of another – millions of them. If examined under a microscope, one will see that a genuine natural or cultured pearl will be composed of scales and ridges. Although these surface irregularities are not visible to the naked eye, one is able to feel their vibration when rubbing a pearl over their teeth.

PS
A grain of sand has nothing to do with a pearl. Actually, the grain of sand theory is an urban legend. Natural pearls are formed by the introduction of organic material, typically a parasite – not a grain of sand.

Answer 2

Real pearls are formed as a result of an irritation in the oyster's "innards"...often caused by grains of sand. Apparently a pro can feel the grit of sand on the surface of a real pearl by rubbing on the biting edge of his/her front teeth, whereas a fake will be perfectly smooth.

Answer 3

Bite it. No seriously, it's a fool proof way of figuring it out. If its grainy when you bite on it then its real. If its super smooth and without any bumps then it's prob. fake. My dad taught me that when I was little lol! works everytime!! =)

Answer 4

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Answer 5

They are not biting them. They are rubbing them across there teeth to feel for the flaws. Fake ones are smooth. really have ridges