Before the 20th century, only the wealthiest of the wealthy could afford diamond rings. One of the first recorded examples of a diamond ring was in 1477, when Archduke Maximilian of Austria gave one to Mary of Burgundy. After that point, diamond engagement rings became a symbol of wealth and prosperity, and accordingly, limited to the furthest arches of the upper class.
The idea that people routinely emptied chamberpots out windows into the street is one of the images of the past that has been taught to generations of school children. It's usually said to have been done in the Middle Ages and it's an image that has stuck with many people, particularly because we find it so disgusting. Unfortunately, like many popular ideas about the Middle Ages, it's largely nonsense.