Things to know when you buy a diamond ring:

First, there are the 4 C's.

Cut

Cut refers to both the shape (round, princess = square, pear, etc) and the quality of the cut.  The more symmetrical the facets are, the more light the diamond will reflect.

Color

The color of diamonds varies from colorless (most rare and precious) to many shades of yellow (less rare).  Colorless diamonds are usually called D, E, or F.  If you want only perfection regardless of price, D is the most expensive.  G, H, and I are the nearly colorless to white diamonds.  Sometimes the white diamonds appear more clear because you are actually seeing color.  J, K, L, and M are yellow diamonds that range in color from palest to strongest yellow.

Clarity

Clarity refers to the inclusions or characteristics inside a diamond.  According to the most common scale:

If you want perfection regardless of cost, go for Flawless (F) or Internally Flawless (IF).  Both are very rare and extremely expensive but possibly the only grade you will always be proud to own if you are looking for perfection.

If you want it to look flawless under a loupe but not pay for flawless, go for VVS1 or VVS2 clarity grades.  These are still flawless to anyone other than a professional grader even under 10x magnification.

If you want to see very little with a loupe and nothing to the naked eye, go for VS1, VS2 clarity grades.  These types of diamonds are certainly flawless to the naked eye, even to a diamond grader. 

If you just want it flawless to the naked eye, go for SI1 or SI2 clarity grades.  Many women really only want this degree of flawlessness, and you will be able to afford a much larger stone for the same price as a clearer stone.

If you don't mind some small inclusions that might possibly be visible to the naked eye and want a larger stone that still sparkles, go for I1 clarity.  You may even find an I1 diamond with inclusions in the edges of the stone, under the prongs of the setting so that they are not noticeable at all.

Carat

Carat refers simply to the weight of a diamond.  Carat weight is actually the last of the four Cs to consider, surprising as this may seem. Although size will be the single most important factor in the price of a stone, it does not affect the beauty. First, decide on the quality you want (the first 3 Cs above), then decide on the largest size you can afford to meet those guidelines.

Good luck and happy shopping!

Another warning about the 4 Cs: When you are shopping, make sure you know what company did the diamond grading.

The most trusted diamond grading company is the Gemological Institute of America. They set up the scales that most graders use. HOWEVER, it is perfectly legal for other companies to grade according to their own scale. They may take a diamond that has large inclusions, which would be an SI or an I by GIA, and call it VSI because that's how their scale is defined. The jeweler may then price a lower quality diamond much higher because it has a rating that we are all familiar with. The jeweler has no obligation to tell you who grades their diamonds. The jeweler is only at fault legally if they intentionally and specifically tell you the wrong grading company.

Do your research, and don't be afraid to ask A LOT of questions. The more knowledgeable you are and the more questions you ask, the less likely you will be taken advantage of. Don't be afraid to ask a jeweler who grades their diamonds and ask to see the definitions of that grading scale. The only person who will ever be offended is someone who is trying to rip you off.

Good luck!

Well, at least you know your fiancée will never be secretly disappointed in your choice.  AND a wedding band is forever, so you won't need any upgrades or anything. 

One thing to consider in the future, though, if y'all are ever shopping for another type of ring, is that platinum is not easily sized.  If your future wife has a tendency to gain or lose weight, or even if y'all are planning on having children, there is a good chance the size of her fingers will change.  For only that reason, I like white gold the best.  No one can tell the difference when they are looking at my hand. 

Good luck with your wedding speech and congrats!

~Jeni

oh wow, thats such a fancy ring, indeed. I wouldnt know what to get if my fiance got me one of those! If we didnt have any money later, i would know why!

And when buying don't be fooled by all that talk that every diamond is unique. Just DeBeers trickery. Buying the diamond shouldn't be any more difficult then buying gold or coffeee for that matter by the pound.  Check this site out before you buy your diamond:

http://www.andersonanalytics.com/diamond.htm

If you think a diamond engagement ring is a good investment, you're a victim of another very effective marketing ploy used by many jewelers to try to make you feel better about spending more than you can afford. The diamond you buy may or may not increase in value, depending on its quality, but investments should not be made in anything as emotionally charged as a diamond engagement ring.

How would you feel about selling the ring if you needed the cash for a new car or to pay off debt? Not very good. So keep your investments separate from the tradition and symbolism of a diamond engagement ring.