Final answer:
Opals can be treated in various ways to improve their appearance, including impregnation, backing, and cutting. Sellers are supposed to disclose these treatments, but this doesn't always happen.
Step-by-step explanation:
Opals are gemstones that are often treated to improve their appearance. There are several types of treatments that can be done to opals, including:
- Impregnation: This involves soaking the opal in a liquid resin to enhance its color and make it more stable.
- Backing: This involves attaching a black or dark backing to the opal to enhance its play of color.
- Cutting and reshaping: Opals can be cut and reshaped to improve their appearance and maximize their play of color.
It is important to note that these treatments should be disclosed when selling opals, but not all sellers may do so, leading to a situation of asymmetric information between buyers and sellers.