Ceramic cutting tools are commonly used in various applications due to their high hardness and wear resistance. These tools are typically made of a mixture of oxides of aluminium, which is the correct answer to this question.

Explanation:
- Ceramic cutting tools are made from a material called alumina, which is also known as aluminum oxide (Al2O3).
- Alumina is a ceramic material that is highly resistant to wear, heat, and chemical corrosion. It has a high melting point and exceptional hardness, making it suitable for cutting applications.
- Alumina is obtained by heating aluminum hydroxide or bauxite ore at high temperatures, resulting in the formation of aluminum oxide crystals.
- The alumina crystals are then mixed with other additives to enhance their properties and increase their strength.
- These additives may include zirconium oxide, titanium oxide, and other oxides, depending on the specific requirements of the cutting tool.
- The mixture is then shaped into the desired tool shape using a process called powder metallurgy, where the powder is compacted under pressure and then sintered at high temperatures to form a solid structure.
- The sintering process helps to bond the alumina particles together, creating a dense and hard material that is resistant to wear and can withstand high temperatures.
- After sintering, the ceramic cutting tool may undergo additional processes such as grinding, polishing, and coating to further enhance its performance and durability.
- The resulting ceramic cutting tool exhibits excellent hardness, high thermal stability, and chemical resistance, making it ideal for cutting, machining, and shaping various materials such as metals, plastics, and composites.

In conclusion, ceramic cutting tools are made of a mixture of oxides of aluminium, primarily alumina or aluminum oxide. These tools offer exceptional hardness, wear resistance, and high-temperature stability, making them suitable for various cutting applications.