There are four key factors that influence the appearance and value of a diamond, collectively called the 4 C's. If you want to select the right stone for your engagement ring and understand the price you're paying for your diamond, then you need to have a handle on each of the 4 C's: cut, color, clarity, and carat.
Cut is the most important of the 4 C's. "Cut" actually refers to the number and placement of facets in the diamond - not the diamond's shape. For example, a square diamond could have the same cut as an elongated rectangle. So before you can even get to selecting the cut of your diamond, you must first pick the shape you want (oval, square, rectangle, etc.)
The most popular diamond cuts are round brilliant, princess, and oval cuts. But there are many others, from vintage to modern to timelessly elegant. Some cuts (like round brilliant) enhance the way a diamond sparkles, while others (like oval and marquise) make a stone look larger.
Not all cuts are created equal, and if you get a diamond report you'll get yours graded. Cuts are ranked on a scale of "ideal," "very good," "good," "fair," or "poor." Because the quality of cut affects the way light bounces off the diamond (thus affecting the perceived brilliance of the diamond,) it's probably a good idea to purchase the highest cut grade in your budget. You certainly don't want to shell out a lot of money for a diamond that ends up looking dull because of a poor cut!
If you haven't shopped for diamonds before, you may not know that all white diamonds aren't actually colorless - in fact, most white diamonds have a slight color that may or may not be visible to the naked eye.
Diamond color is graded on a letter scale: the less color, the more rare and expensive the diamond. The grading scale for white diamonds is as follows:
D - absolutely colorless (very rare)
E - colorless, only minute traces of color can be detected by an expert gemologist (also rare)
F - minute traces of color can be detected by an expert gemologist
G-H - near colorless, color is only detectable when compared to a more colorless diamond
I-J - near colorless, slightly detectable color
K-M - faint color noticeable
N-Z - noticeable color
(Note that this scale is only for white diamonds! There is a different grading scale for colored diamonds.)
It's important to note that certain features of your diamond can affect how much the color "shows." Larger diamonds tend to make color more noticeable, while cuts with more sparkle (such as round brilliant) tend to mask it.
Almost all diamonds have tiny imperfections, either on or below the surface. Clarity is determined by number and size of these imperfections under 10X magnification. The fewer blemishes and imperfections in the stone, the better the clarity and the more valuable the diamond.
"Imperfection" and "blemish" sound like terribly ugly words, but most are so small that they don't affect a diamond's beauty at all. Most aren't visible to the naked eye, and untrained individuals may not even be able to see them under a microscope. Out of the 4 C's, clarity is generally regarded as having the least impact on the appearance of your diamond.
The GIA grading scale for diamond clarity is:
FL (Flawless) - no internal or external imperfections
IF (Internally Flawless) - no internal imperfections
VVS1, VVS2 (Very, Very Slightly Included) - very difficult to see tiny imperfections under 10x magnification, not visible to naked eye
VS1, VS2 (Very Slightly Included) - slightly difficult to see small imperfections under 10x magnification, may be visible to naked eye
SI1, SI2 (Slightly Included) - fairly easy to see imperfections under 10x magnification
I1, I2, I3 (Included) - imperfections range from just visible to very easily seen by the naked eye
Certain diamond cuts are more transparent than others, requiring a higher clarity diamond. Less brilliant cuts like asscher and emerald are a few examples. Also note that larger diamonds require a higher clarity too, because the size of each facet (hence, the transparency of the diamond) increases as the diamond gets bigger.
Carat is the term used to give the weight of a diamond. One carat equals 200 milligrams, or 1/5 of an ounce. This means that the higher the carat weight, the more expensive the diamond. Remember that carat is a weight measure; it doesn't necessarily describe how big your diamond will look once it's set in the ring. A deep diamond with more carats, for instance, will look smaller than a shallow diamond with less carats.
There's no price-per-carat formula when it comes to diamonds. Large diamonds are rare and smaller diamonds are more common, so a single 1-carat diamond will cost much more than two.5-carat stones. Buyers on a budget should consider a ring with a cluster of smaller-carat diamonds, rather than one large stone with a high carat weight.
It's helpful to know that prices usually jump at the full-carat and half-carat marks, meaning that a.47 carat diamond may be significantly less expensive than a.5-carat one that is almost identical in size.
Carat weight is actually one of the least important elements of your engagement ring diamond, and should be easy to select once you've decided on the other C's of the diamond you want.
To know and understand the 4 C's of your diamond, you should always get a diamond report from an independent gemological association like the GIA (Gemological Institute or America) or AGS (American Gem Society.) The report will help you evaluate all aspects of your diamond and make an informed decision on this very important purchase.
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