After your house and car, the ring may be your third most important purchase. Notice that I said important not expensive. It doesn't have to be that expensive. You do want it to be the best quality and size that you can afford. Today's couples don't use the old purchasing formula based on the mans 3 months salary, but most do consider their future income and life style. Although some couples choose to upgrade to better rings as years go on, I find that most women prefer to stick with her original ring for sentimental reasons. So, lets get it right the first time.
The cost of a diamond depends upon the qualities of size, shape, color, clarity and cut of the stone. A small change in these qualities can make a huge price change.