Bi-coloured sapphires typically feature two distinct colours that are clearly separated within the stone. This colour zoning is often seen as bands or sections of different hues, such as blue and yellow or green and orange. The transition between the colours can be sharp or softly blended, but it remains limited to just two colours.
Parti sapphires, on the other hand, display two or more colours that blend and shift depending on the light and angle. Most Australian parti sapphires feature blue, green, and yellow in various combinations, often creating a mesmerising interplay of colours. Unlike bi-coloured sapphires, parti sapphires can showcase multiple shades within the same facet, giving them a unique and dynamic appearance.
