Lesson6: Pearl Coating Techniques
a. Overview of Coating Treatment
Pearl coating treatment refers to applying one or multiple thin layers artificially to the surface of pearls. This process enhances luster, changes color, or provides additional protection. It is typically used for pearls of lower quality to increase their market value or meet specific decorative requirements.
b. Characteristics and Considerations of Coated Pearls
1. Appearance Features
Coated pearls often exhibit a distinctive iridescence or rainbow-like shimmer. The luster may sometimes appear unnatural or shallow, similar to the plastic film found on inexpensive costume jewelry. Particularly around drilled holes, you might notice a thin, transparent layer, which is a key indicator of a coated pearl.
2. Durability Issues
The durability of coated pearls is generally inferior to natural pearls. According to research, coated pearls start showing signs of peeling after approximately two years of wear. Without regular professional care, peeling may occur within 6 months to a year. Long-term wear can also result in oxidation or discoloration.
3. Types and Techniques
Various materials and techniques are used for coating, such as resin, metal, or other compounds. These different coatings impact the pearl’s final appearance and durability. For instance, resin coatings can enhance luster temporarily but have low hardness, making them prone to abrasion and typically lasting only 3 to 6 months.
4. Distinguishing and Identification
There is a significant difference in value between coated pearls and natural pearls, so caution is required when purchasing. To identify coated pearls, observe if the luster looks natural, and check around drill holes for any unusual film. Consulting a reputable appraisal agency for professional evaluation is also recommended.