Why does glass sometimes appear green?

This particular question relating to why glass sometimes appear green is a relatively common question we get about glass.
The greenish tint on glass table tops and glass table covers comes from the iron content used in the manufacturing process. This is typical of all glass table tops and table covers in the furniture industry, and is known as clear glass. This greenish tint is most noticeable when looking at the glass piece from the edges.
If this is something you prefer to avoid, you can opt for low-iron glass. Low-iron glass has all the same properties as clear glass, but the low iron content means a clearer look and substantially less greenish tint.