I have heard over and over again about the "two month salary" guideline for purchasing a diamond. Is this a good rule to go by, is this what most people use? I hate to sound like I want to "keep up with the Joneses" but most of my friends have bought rings that I know are way in excess of two months salary.On the DeBeers site they have a calculator where you plug in your yearly salary and then they come up with a number. I did that and that way it came out to like 4 months salary.