1, look at the color, the color of dyed pearls is dignified and dull, and there will be color enrichment where holes and defects are drilled. The color distribution along the crack is easy to observe near the hole, and the bead line often rubs out the color of the dye. Traces of dyes can be seen in the pearl holes, especially there is an obvious dyeing line at the junction of mother-of-pearl layer and pearl core.

2, look at the color spots, the density of mother-of-pearl can not be completely consistent, and the pigment of dyed pearls will precipitate at a relatively low density, which will form color spots. Stains have obvious dividing lines, which may leave obvious pigment deposition in some defective parts. Some dyed beads may not see stains clearly in natural light, but in strong light, stains are inevitable.

3. Internal structure: Under the reflected light, there are often interference halos under the thin pearl layer on the dyed pearl surface. This phenomenon may be caused by film interference caused by dye infiltration into nacre.

4, chemical testing, with a concentration of 2% dilute nitric acid dipped in cotton swabs to wipe pearls, silver nitrate dyed pearls quickly dyed cotton swabs, and sometimes even alcohol cotton swabs can erase their color. However, this method does do some damage to pearls, so please be careful!

Extended data

The color of pearl includes three parts: pearl body color, pearl companion color and halo color.

The body color of pearl refers to the primary color (i.e. background color) of pearl, that is, the color produced by pearl's selective absorption of white light, which is determined by pigment and trace metal elements contained in pearl.

The companion color of pearl refers to the unique color of pearl formed by the comprehensive effect of reflection and interference of light on the surface and inner layer of pearl, and the companion color is superimposed on its own color. The accompanying colors are generally rose, blue, green and colorful halo. Halo is a drifting rainbow color formed under the surface of pearl. Mainly composed of pink, green, yellow, orange, blue, purple and other colors of the rainbow.

Generally speaking, the color of pearls can be divided into five color systems according to their body color. They are white series, pink series, gold series, black series and other colors. However, even if different kinds of pearls have the same body color, there are still differences between companion color and halo color, so Bian Xiao, a pearl beauty network, will tell you that there are several colors of different kinds of pearls.

1. Freshwater pearls: The colors of freshwater pearls are mainly white, pink and purple, among which the common colors are pure white, beige, pink, purple and pink orange.

In terms of color, freshwater pearls are usually accompanied by some other colors, such as yellow, pink or blue. At present, there are new varieties of nucleated freshwater pearls-Edison pearls, which also have special metallic halos such as deep purple, violet and bronze.

2. Seawater pearls: The colors of seawater pearls in China are mostly white and yellowish, and the main colors are red, cyan, purple, brown and black.

The seawater pearls in Japan are mainly white, and the common ones are beige, champagne and light gold. Generally speaking, the white seawater pearls in Japan are white with pink, silver blue and other foil colors, and their colors give people a pink feeling. In addition, Japanese seawater pearls have a very special color, which is gray. Natural silver-gray pearls from the deep sea are very rare.

3. Tahiti Black Pearl: The so-called Tahiti Black Pearl is not pure black. The body colors of black pearls are black, blue-black, gray-black, brown-black, purple-black, brown-black and iron-gray. The darker the hue, the larger the value.

Black pearls have rainbow-like pearlescent colors in the basic colors of black and gray, generally accompanied by metallic colors such as navy blue, deep purple, malachite green and brown gold. The most unique color is brilliant malachite green, and the most unique color is brilliant malachite green. Its strong metallic luster will change with the rotation of pearls, which is incomparable to pearls of other colors.

4. Nanyang Pearl: The main colors of Nanyang Pearl are gold and white. At present, the common colors of Nanyang pearls on the market are generally gold, champagne, cream, white, pink white, silver and pink silver. Nanyang pearls are pure in color and have inherent natural beauty, and do not need manual processing such as bleaching and dyeing.