The correct answer is option 1, Ferric oxide.
Jeweller`s rouge is a type of polishing compound commonly used by jewelers to achieve a high shine on metals, especially precious metals like gold and silver. It is also used by metalworkers for polishing various metal objects.
Ferric oxide, also known as iron(III) oxide or hematite, is the main component of Jeweller`s rouge. It is a reddish-brown or black powder that is insoluble in water and has strong abrasive properties. When applied on a polishing cloth or wheel, the fine particles of ferric oxide help to remove scratches, imperfections, and dullness from metal surfaces. It creates a smooth and reflective finish, enhancing the appearance of the jewelry or metal object.
Although options 2 to 4 mention different types of iron compounds, they are not the correct answer for Jeweller`s rouge. It is important to note that Ferric oxide is the specific compound used in this polishing compound.