Colour is by far the most important factor when valuing a pink diamond. The stronger the saturation level and brighter the tone, the rarer the stone.
Pink diamonds are graded 1-9 based on their saturation, with 9 being almost white, and 1 being the most saturated. This is combined with the letters P (Pink), PR (Pink Rosé) or PP (Purplish Pink) to signify the hue.
Champagne pink diamonds are graded slightly differently, on a scale of 1-3, with 3 being the most white, and 1 being the most saturated. This is the reverse of Pink, Pink Rosé and Purplish Pink diamonds. This is combined with the letters PC (Pink Champagne) or CP (Champagne Pink) to signify the hue.