Optimization treatment and identification: Natural turquoise is usually modified by wax injection, dyeing and injection molding. This practice is usually not recognized by the jewelry industry because it changes the nature of turquoise.

1. dye ...

(1) dyed turquoise is unnatural in color. Turquoise dyed in the domestic market is often dark blue or dark green, which is too uniform, but the color becomes darker at the crack.

⑵ The dyed turquoise is very light in color, generally around 1mm, and light-colored nuclei may be exposed in some places.

2. Spray molding method

Injection molding includes injection of colorless and colored plastics. Turquoise treated by injection molding (figure 12-5-7) can be identified by the following points:

⑴ Refractive index: Generally, injection molding will be lower than 1.6 1.

⑵ Relative density: The relative density of injection molding is relatively low, generally less than 2.76.

⑶ Hardness: The Mohs hardness of injection molding is generally 3-4, and the injection-molded turquoise is prone to scratches.

(4) Infrared spectrum: We can observe the strong absorption between 65,438+450 cm and 65,438+500 cm caused by plastic, while the new injection-molded varieties have a strong absorption band of 65,438+725 cm.