Overtone is the subtle color that occurs naturally in a pearl. The body color is still the main color, and the first thing you see. However, the overtone is secondary, and is noticeable by anyone looking at the pearls.
Some of the most popular overtones on white pearls are rose, ivory, and silver. These overtones are found on Akoya pearls and white Freshwater pearls. The rose overtone has a pinkish hue over a white pearl. The ivory overtone is sometimes described as a cream color therefore the pearl appears a little off white. The silver overtone adds a kind of sheen to the pearl. This overtone on a white pearl can give the appearance of the purest or brightest white. Akoya Overtone Options: Top to Bottom: Ivory, Silver and Rose.
Black Akoya or Freshwater pearls often have overtones of Blue, Purple or even Brown. Tahitians Pearls have a huge array of color shimmering as an overtone including green, purple, red, yellow etc.