For years, the diamond industry has tried to subconsciously sell the idea that you should spend no less than two (2) months salary on your engagement ring. Actually, they must've done a good job at spreading this belief as it's now generally acknowledged as the norm by nearly everyone.
According to that theory, if you make $ 180,000 per year, you should spend $ 15,000 on a diamond engagement ring. That sounds reasonable and you can probably afford it. But will your future wife want to possess and carry such an expensive ring? won't she be afraid of losing it or getting it stolen? $ 15,000 will get you a very large diamond and you mightn't want such a big stone. "The bigger, the better". Maxim doesn't apply to diamond rings. In contrast, as per the theory, if you make $ 18,000 per year, you should be spending about $ 3,000. That sounds like a lot of money. it's quite unreasonable to spend this much money on a ring when you might be worried about basic necessities.
Things to consider before you spend an important amount of money on a ring:
–. Do you've any important payments coming up?
–. Is your job guaranteed?
–. If you've kids, have you thought about their future?
–. Does your future wife desire a big diamond ring or a regular band?
–. Does your future wife have to work with her hands? Will a big stone be encumbering?
–. Have you thought about the cost of the wedding itself?
Don't worry about the silly two months theory. You can get the perfect engagement ring for a fraction of what the diamond industry wants you to spend.
Another alternative is to discuss the situation with your future wife! she'll see you as a responsible future husband and won't mind discussing it with you. After all, she'll wear it every day for the rest of her life (hopefully). it's better if the ring meets her needs and desires.
The advice won't work with everyone. Some girls want to get proposed to a romantic setting and it may ruin it if the guy starts discussing the size of the diamond that she wants with him. So it's unfortunately not a perfect science. You'll have to decide whether you want to surprise her or if you want to insure her satisfaction of the ring.
Finally, remember that the size (or the expected size) of the ring is often heavily dependent upon culture. If you're not going to discuss it with her, you can ask your friends, her friends or even her family. Good luck!