Final answer:
Emeralds, with their deep green color, are recognized as the birthstone for the month of May. They are often treated to enhance their look, and such treatments should be disclosed to the buyer.
Step-by-step explanation:
The emerald is a precious gemstone known for its vibrant deep green color, which makes it a sought-after jewel. Each month is traditionally associated with a specific gemstone, known as a birthstone, which is said to bring good luck to people born in that month. For the month of May, the birthstone is the emerald. These gemstones, including emeralds and rubies, often undergo treatments such as oiling or the use of epoxy to enhance their appearance and durability.
However, such treatments should always be disclosed to buyers, especially since non-disclosure can lead to a situation of asymmetric information in an economic transaction, meaning that the seller knows more than the buyer. Nonetheless, the allure of emeralds remains untarnished, with their rich color attributed to trace amounts of chromium (Cr3+) impurities within their crystalline lattice.