May's birthstone is emerald. Emerald is a gemstone with a distinctive deep green color, and is highly valued for its beauty and rarity.

Emerald is a type of mineral called Beryl. It has a distinctive bright green color due to the presence of trace impurities such as iron and chromium. The color of emeralds is evaluated by their intensity and transparency, and those with deep green color and high transparency are the most valuable.

Emeralds have been prized since ancient times and were widely used as jewelry for royalty and nobility. Emeralds are also a symbol of good luck and love, and are popular as wedding rings and special gifts.

Emeralds generally contain many inclusions. This is a natural feature and is also taken into account when determining the beauty and rarity of an emerald. Clean emeralds are extremely rare and expensive, and those with few inclusions are especially valuable.