Which colour is shown by the permanganate ion?

Actually, the Permanganate ion shows a purple colour.

Potassium permanganate

Potassium permanganate is an oxidising agent with disinfectant, deodorising and astringent properties. Its chemical formula is KMnO₄. KMnO4 has a deep purple colour. The metal ions in KMnO₄ contains d electron and, therefore, charge transfer occurs from O^– to Mn⁺. The colour of KMnO₄ is due to charge transfer transitions by absorption of visible light.

• Potassium permanganate is used extensively in the water treatment industry.
• A major application of KMnO₄ is as a reagent for the synthesis of organic compounds.
• Potassium permanganate is one of the principal chemicals used in the film and television industries.