The beauty and value of coloured stones depends on where their colour lies within a particular colour spectrum. It’s helpful to compare stones within the same species, sapphires with sapphires, rubies with rubies etc. Certain colours are more desirable. Top colours within the trade are described as having fine colour. Sapphires for example have a large colour range, however only those that lie between certain parameters would be considered fine. Body colour is a mixture of tone, hue and saturation. Hue is the basic overall colour, blue, red, yellow, green. When a stone has another colour coming through like a “purplish red” another colour is present. Stones that have one overall hue are generally more valuable than stones with a combination of hues face up. Pure red in a ruby is more favoured than ruby with strong secondary hues of orange or purple. Unlike muscles tone in a stone is how light or dark it is. Some sapphires are so dark they look almost black. The third wheel of colour is saturation. This translates as the strength or intensity of the colour. All these combinations of hue, tone and saturation determine a coloured stones value. Have a look below to compare colours of sapphires here at CM Weldon in powerscourt townhouse centre, Dublin 2.