Harvard University has collection of 2,500 rarest colours

The Harvard Art Museums, which are a part of the Harvard University in the United States, feature a collection of around 2,500 rarest colours. The collection includes pigments like 'dragon's blood', 'mummy', 'Indian yellow' and 'dried urine of cows'. The pigments are small particles of coloured material, which are mixed with a binding medium to give colour to paint.