Question

Which of the following is NOT a gem-stone?
Marble
Topaz
Opal
Pearl

Answer 1

Marble.

Hope it helps you

Answer 2

$\mathfrak{\large{\underline{\underline{Answer :}}}}$

Marble

Marble is not a gem stone.

$\mathfrak{\large{\underline{\underline{Additional Information : }}}}$

• Gemstone is a piece of crystals of mineral, which are shaped, cut and polished to make them eligible to be used in ornaments and other adornments.

• The gems who don't have minerals in them but though are used in jewelleries are also considered as gemstones.

• Topaz can be found in yellow, orange, brown, pink to red to purple red, blue, light green colours. There are colourless Topaz too.

• Topaz is a pleochroic gem, which means that the gem shows different colors in different crystal directions.

• Opal is the most popular stone in the world. It is a stone which can flash every color of the spectrum with quality of color.

• Opal is softer than most other popular gemstones.

• Pearls are known by their translucence and shine and by a surface colour called orient. 

• The value of a pearl is decided by its shape and lustre. If the shape is perfect with deep lustre the value of the pearl would be greater.

• Marble is a rock type. It is a metamorphic rock.

• They are made up of recrystallized carbonate minerals.