Why measure sugar colour?

One of the most important quality parameters in sugar trade is the colour of the sugar, because the colour gives an indication of how pure the sugar is. Pure sugar is white. The impurities are coloured, so sugar with an intense colour has lower purity.
When sugar is used as an ingredient, the impurities may influence the properties of the manufactured product. Therefore, many users of sugar have strict limits on the amount of colour they will tolerate.