Which of the following is not a precious/semi-precious stone? A. Sapphire B. Ruby C. Pearl D. Emerald

The correct answer is C.

Pearl.

A

precious stone is a rare, naturally occurring, hard, colored gemstone, typically having a specific crystalline structure. The most well-known precious stones are diamond, ruby, sapphire, emerald, and alexandrite.

A semi-precious stone is a gemstone that is less valuable than a precious stone. Semi-precious stones are often used in jewelry, but they are not as rare or as expensive as precious stones. Some examples of semi-precious stones include amethyst, garnet, topaz, and turquoise.

Pearls are not considered to be precious or semi-precious stones. They are formed when an irritant, such as a grain of sand, enters an oyster and the oyster secretes a substance called nacre to coat the irritant. Over time, the nacre builds up and forms a pearl. Pearls are valued for their beauty and rarity, but they are not as hard as precious or semi-precious stones.