Because food colouring always produces a matt colour, your attempts to make a metallic silver icing will be in vain. However, there's a way around this problem -- you can dye the icing a beautiful grey colour and add a silvery finish by stirring in edible silver glitter. Edible glitter is available in different sizes and shapes, such as hearts and stars. Sprinkle extra glitter on top of your iced baked goods for added drama.
Place 45 ml (3 tbsp) of white icing in a small bowl. Practice tinting the icing grey by adding drops of food colouring, alternating one drop of black with one drop of blue. Stir the icing after each set of two drops and check the colour.
Empty the whole packet of icing into a large bowl. Drop in the food colouring as you did in the previous step, alternating drops of the two colours and stirring while keeping an eye on the icing colour. Stop just before you see the depth of colour you want to achieve, because the icing will get darker as it sets.
Sprinkle in 5 ml (1 tsp) of edible silver glitter and stir. Check the colour and continue adding edible glitter in 5 ml (1 tsp) increments until you've reached the desired effect.
Use the silver icing to decorate your cake or cupcakes. Store the baked goods in the fridge until ready to serve.