Among the following, which is the odd one out: Sapphire, Ruby, Topaz or Granite?

Introduction / Context:
This is a general knowledge and classification question. You are asked to choose the odd one out among four given names: Sapphire, Ruby, Topaz and Granite. Problems like this test your awareness of everyday terms, materials and categories, rather than numerical reasoning.

Given Data / Assumptions:
The options are four common names associated with stones or minerals: Sapphire, Ruby, Topaz and Granite. We assume you know that some of these are precious or semi-precious gemstones, while others are ordinary rocks used in construction and industry.

Concept / Approach:
The key idea is to classify each item into its correct category based on basic general knowledge. Three of the items belong to the same category (gemstones used in jewellery), while one belongs to a different category (an igneous rock used mainly as a building material). The item from the different category is the odd one out.

Step-by-Step Solution:
Step 1: Consider Sapphire.Sapphire is a precious gemstone, typically blue, composed mainly of the mineral corundum. It is widely used in jewellery.Step 2: Consider Ruby.Ruby is also a precious gemstone made of corundum, distinguished by its deep red color. It is a classic gemstone in rings and necklaces.Step 3: Consider Topaz.Topaz is a silicate mineral, valued as a semi-precious gemstone. It comes in various colors and is also commonly used in jewellery.Step 4: Consider Granite.Granite is a coarse-grained igneous rock composed mainly of quartz, feldspar and mica. It is used for countertops, flooring, paving and as a construction material. It is not classified as a gemstone.Step 5: Therefore, three items (Sapphire, Ruby, Topaz) are gemstones, and one (Granite) is an ordinary rock primarily used in construction.

Verification / Alternative check:
You can cross-check by thinking about where you usually see each of these. Sapphire, Ruby and Topaz are seen in rings, pendants and other jewellery pieces, and are sold in jewellery shops. Granite, however, is seen in kitchen slabs, tiles, monuments and building facades. This everyday knowledge confirms that Granite belongs to a different category from the other three.

Why Other Options Are Wrong:
Sapphire, Ruby and Topaz all share the property of being gemstones used as ornaments. Removing any of them as the odd one out would leave two gemstones grouped with a construction rock, which does not make sense from a classification point of view. Therefore, they cannot be correct answers.

Common Pitfalls:
Sometimes candidates may be unsure whether Topaz qualifies as a gemstone or may focus on color or price differences rather than basic classification. The safest and most objective way is to check whether each name refers to a gemstone or to a common rock. Once that is done, the answer becomes clear and unambiguous.

Final Answer:
The odd one out, because it is a rock used mainly in construction and not a gemstone, is Granite.