What Colors Do Pearls Come In, and What Is Overtone?

Color is one of the seven value factors used to judge natural and cultured pearls,² and the one most often changed by treatment.⁴

Bodycolor, overtone and orient#

GIA describes pearl color as having up to three parts:²

• Bodycolor is the pearl’s dominant overall color.²
• Overtone is one or more translucent colors lying over the bodycolor. Overtones are typically pink, sometimes called rosé, green, purple or blue.^{2 3}
• Orient is a shimmer of iridescent rainbow colors on or just below the surface. CIBJO explains it as interference and diffraction of light from within the surface of some nacreous pearls.^{2 5}

All pearls have a bodycolor, but only some show overtone, orient or both.²

Where pearl color comes from#

CIBJO’s guide describes a pearl’s color as a mix of two things. One is interference color, made as light reflects, bends and interferes in the many fine crystal layers of the nacre. Depending on how thick those layers are, a pearl may show pink or green interference colors, closely tied to its luster. The other is bodycolor.⁴

Bodycolor comes from pigment. In Akoya cultured pearls it comes from pigment in the conchiolin, the organic matrix of the nacre,⁴ and a pigment called uroporphyrin is one cause of gray to black tones in some pearl oysters.⁶

Farmers can steer it. In Akoya culturing, yellow is reduced by taking the graft from donor oysters with the least yellow pigment.⁴ In freshwater culture, the color of the donor mussel’s mother-of-pearl strongly shapes the color of the pearl.⁷

Some color comes from deeper inside. In some Akoya, blackish-brown organic matter between the nacre and the bead looks blue when seen through the nacre.⁴ Usually, but not always, natural pearls have the same color as the mother-of-pearl of the mollusk that made them.⁵

The natural colors of each pearl type#

Each type has its own range of natural colors. The table gives them from the Learn About Pearls dataset.

• Akoya are white or cream, often with a pink overtone, and that pink is very often the result of processing.^{9 10}
• Freshwater pearls come in a wide range of pastel colors, mostly shades of pink and orange, and some look multicolored or metallic.⁹
• South Sea pearls are white to silver or golden, depending on the oyster: white from the silver-lipped oyster and golden from the gold-lipped.^{3 14}
• Tahitian pearls are gray, black or brown, and greenish gray is the most common color.^{3 9}

How color affects value#

There is no single right color. CIBJO says the same color may be prized in one place or time and not another, depending on rarity, fashion, nationality or regional taste. In the end, color comes down to the wearer’s preference.⁴ GIA adds that supply and demand set the value of a color at any time, while fashion and tradition shape which colors people like.²

Color also matters for matching. In strands and other jewelry with several pearls, the pearls should usually match in color as in the other factors, though designers sometimes mix colors on purpose.²

How color is described and graded#

There are no unified standards for pearl color names, and each vendor uses its own naming system; for Akoya, pink, white, green, cream, gold and blue are common names.⁴ GIA’s graders judge color against master sets that include a hue circle and color grids.¹⁵

Natural or treated color?#

Color is the quality factor most affected by treatments. Dyeing, irradiation and coloring change color directly, and maeshori, bleaching and choshoku, a light color adjustment after bleaching, also affect it.⁴

Golden South Sea color can be natural or made by heat or dye.^{12 13} “Chocolate” pearls were most likely bleached from black cultured pearls.¹⁶ And some gray or blue Akoya are irradiated.¹⁷ The page dyed and treated pearls explains how labs recognize treated pearls.

Color can also change with time. Pearls are made by living animals, and CIBJO notes that all natural and cultured pearls are known to change their color appearance over time.⁴ Some colors, natural or treated, can fade in sunlight, artificial light or strong display lights.⁵