Free CGC Gemstone Identification & Classification Questions and Answers

Question 1

What is the main characteristic used to classify gemstones?

Accepted Answer

Chemical composition

Answer

Gemstones are primarily classified by their chemical composition, which determines their fundamental properties like crystal structure, hardness, and optical characteristics. While color, hardness, and origin are important identifying features, the underlying chemical makeup is the most fundamental criterion. This scientific classification provides a consistent basis for understanding gemstone properties.

Question 2

Which gemstone is known for its hardness of 10 on the Mohs scale?

Accepted Answer

Diamond

Answer

Diamond is renowned for being the hardest natural substance on Earth, scoring a perfect 10 on the Mohs scale of mineral hardness. This exceptional hardness makes it highly durable and resistant to scratching, contributing significantly to its value and suitability as a gemstone in jewelry. Its unparalleled hardness is a defining characteristic.

Question 3

What gemstone is most commonly associated with healing properties?

Accepted Answer

Amethyst

Answer

Amethyst is widely associated with healing properties, particularly in crystal healing and spiritual practices across various cultures. It is believed to promote calmness, balance, and peace, and is often used for stress relief, enhancing intuition, and fostering spiritual growth. Its soothing purple color contributes to its perceived therapeutic qualities.

Question 4

What is the term for the effect where a gemstone exhibits a cat's-eye appearance?

Accepted Answer

Chatoyancy

Answer

Chatoyancy is an optical phenomenon observed in certain gemstones, where a sharp, luminous band of light, resembling a cat's eye, appears to glide across the surface when the stone is moved. This effect is caused by the reflection of light from parallel fibrous inclusions or structural growth within the gemstone. It creates a distinctive and desirable visual quality.

Question 5

Which of these gemstones is classified as a precious gemstone?

Accepted Answer

Ruby

Answer

Traditionally, precious gemstones include diamonds, rubies, sapphires, and emeralds, due to their rarity, exceptional beauty, and historical value. While opal, garnet, and amethyst are beautiful and valuable in their own right, they are generally classified as semi-precious gemstones. Ruby's inclusion in the 'precious' category reflects its high demand and historical significance.

CGC - Certified Gemstone Consultant Practice Test

CGC - Certified Gemstone Consultant Practice Test

Free CGC Gemstone Identification & Classification Questions and Answers