The one guideline for purchasing a diamond engagement ring is that it requires two month’s salary. But keep in mind that this is merely a guideline. Because a diamond engagement ring is one of the most important – and often one of the largest – purchases you will make in your life, you want to be sure you do it right. And when doing it right, do not forget that this is a one-time purchase that happens to never wear out, never lose its sparkle and will continue to be a family heirloom that can be passed down from generation to generation.