Did you know that in certain (limited) circumstances you can trademark a colour? Colours can be used to differentiate products. In Australia, marketers and companies have shown interest in gaining trade mark protection for the use of some colours. Think Cadbury Chocolate. As with most trademarks, that use has to be on a commercial basis and is restricted to a particular class of goods or services. Goods and services are defined in the Trade Marks Act 1995.
However, as with the case of Cadbury, it must be a specific colour on the Pantone scale. In 2012 the UK High Court ruled that Cadbury could get trademark protection for a specific shade (Pantone 2685C). This means a company cannot “own” all the shades of purple. The decision does however stop a competitor from using that (or a confusingly similar) shade in their marketing.
So rest assured, Cadbury can’t force you to pay a licence fee if you wear a jumper that your granny knitted in the colour purple. (There may be an issue if she reproduced a chocolate bar on it).