Diamonds by Design - Certified Gemologists

Just what determines a diamond's value anyway?


The value of a diamond is determined by the famous 4 C's: color, clarity, cut, and carat weight. It is the combination of these four items that give a diamond its value. Although carat weight is the best known, a smaller diamond can be more valuable than one several times larger, depending on how the stone is rated on the other three elements. Let's consider these elements one at a time.



Diamonds are found in all colors of the rainbow, although those that are essentially clear are the ones most people think of. Diamonds that have very intense coloration are termed "fancy" in the trade, and demand very high prices from collectors. (How high? It's easy to be talking millions here, so if you're at an auction for fancy diamonds, be sure you are sitting on your hands.) One of the most famous diamonds in the world is a colored diamond, the intense blue Hope diamond in the Smithsonian collection.

Among commercial, non-fancy stones, gem diamonds are graded from colorless (white) to yellowish. The very highest grading is completely colorless. These stones are often referred to as "Blue White", and are quite rare--and very expensive! In the letter grading scale developed by the Gemological Institute of America, a blue white colorless diamond is graded as a "D". (It's a very long story as to why the GIA grading system starts at D instead of A. Unless you are studying to be a gemologist, trust us--you don't want to know.)

At the very other end of the scale are the brownish yellow diamonds, sometimes referred to as "Dark Cape", which on the GIA scale weigh in as in the range from R to X. (You'll notice we're missing Y and Z from this end of the scale. Go figure.) Dark Cape diamonds cost a small fraction of a Blue White diamond of equivalent quality on the other three C factors.


Color Grading of Diamonds



D Blue White
E Fine White
F White
G Commercial White
H Top Silver Cape
I Silver Cape
L Cape
O Light Cape
R-X Dark Cape


All rather confusing, isn't it. To cut to the quick, if you want something that for most people will look colorless or white, you're probably best buying something higher that I on the color grading scale. On the other hand, recently diamonds in the various Cape grading ranges have become quite popular as fashion jewelry, being marketed with such names as champagne diamonds or cognac diamonds. If you would like some more perspectives to help you make a buying decision, see the discussion on which diamond to buy, found elsewhere in Cyberspace.



Clarity refers to how free of inclusions the diamond is. Most diamonds have small inclusions, usually small spots of carbon. These are often called flaws, but there are other types of flaws as well, such as fractures. Inclusions that are so small as to not be seen under 10 power magnification are considered to not exist when it comes to grading. Said differently, if you can't see an inclusion under 10 power magnification, the stone is said to be flawless, even if you could find inclusions under, say, 15 power magnification.

Just as with the letter grading scale for color, there is also a letter grading scale for clarity.

Clarity Grading of Diamonds

IF (Internally Flawless)
No inclusions visible under 10 power magnification
VVS (Very, very small inclusions)
Extremely small inclusions that under 10 power magnification are visible, but are very hard to find
VS (Very small inclusions)
Inclusions that are very small, but will be easy for an expert to find under 10 power magnification
SI (Small Inclusions)
One or more small inclusions that are easily recognizable under 10 power magnification, but not easily visible to the naked eye.
I (Imperfect)
Inclusions that are immediately visible under 10 power magnification, and may be visible to the un-aided eye.

Precise, isn't it? (slightly this, noticeably that!) If we haven't put you to sleep yet, hang in there with us just a moment more. Before we go on with something a little more helpful, we should let you know that these divisions are further broken down by gemologists with the same level of incredible objective precision as detailed above. For example, you will hear about VS1 or VS2 stones. For our purposes, just figure that a VS1 has slightly fewer inclusions than a VS2.

How do you make sense out of all of that? Well, if it's a higher rated stone than I (Imperfect), you will not normally notice any inclusions with the naked eye, and therefore any inclusions will not detract from the beauty of the stone to most people who see it.

Clarity Enhancements


Within the past few years, clarity enhanced diamonds have become broadly available at prices about 30% less than similar, non treated stones. What is clarity enhancement, and is it a diamond to consider?

Clarity enhancement is, quite simply, a way to cover up imperfections in a stone. Clarity enhancement includes two broad treatments, fracture filling and laser treatment. Fracture filling is a way to fill a cavity or fracture in a stone with an artificial,polymer material. The fracture or cavity is still in the stone--it's just harder to see. Fracture filling is not permanent, but it does usually last several years, and most of the companies that sell fracture filled stones will retreat them if the filling is destroyed. A fracture filled stone is usually safe, unless the fracture extends through a large part of the stone. If that type of fracture is present, the stone should be avoided, unless you wish some day to unexpectedly own two, smaller diamonds

Lasering a stone consists of using a laser beam to drill out the inclusions that are visible to the naked eye, making the stone appear to have a higher clarity rating than it actually does. This treatment is almost always permanent.

By law, any type of clarity enhancement must be disclosed to the purchaser. As long as you are aware of what you're buying, there's no particular reason not to consider a clarity enhanced diamond. Keep in mind, though, that these stones are not truly bargains in the sense of getting something for nothing, and should not be compared with an untreated diamond. They are lower qulaity stones, of lower value, sold at a lower price. On the other hand, if you are looking to get the most flash for your buck, a clarity enhanced stone may be for you.



Cut refers partly to the shape of a stone, but even more to the precison proportions and symmetry of its facets.

Ultimately, the real value of a diamond traces its fire--how well its breaks light down into the colors of the rainbow. The more colorless the stone and the clearer the stone, the more brilliant the fire, thus explaining the impact of those factors on value. Cut, too, has a tremendous impact on fire. The facets of the stone reflect the light traveling through the stone. If the angles and proportions are just right, most of the light that enters the stone gets broken apart into the colors of the rainbow and reflected back out through the top of the stone, giving tremendous fire. If the angles or proportion of the stone are a bit off, then some of the light is allowed to escape through the bottom and sides of the stone, reducing the stone's brilliance. This lack of precision in the cut is not always an accident. Some cutters purposely facet a stone imperfectly, to maximize the weight of the finished stone. The idea here is that most untrained buyers of diamonds value carat weight higher than cut, so the stone is cut to maximize the carat weight, even if this makes the stone less brilliant--and therefore less valuable! Caveat emptor.

Different shapes also affect the stone's fire. The cut with the greatest fire is called the brilliant (round) cut. This is the perfect cut for a diamond due to its use of angles that the light travels. These angles are the result of the shape (round) and the placement of the diamond's facets.

Stones are graded for cut into one of four categories--very good, good, medium, or poor. Stay away from poor--it detracts too much from the beauty of the stone. The choice among the others depends largely on your budget.

Carat Weight


The weight of a diamond is measured in carats, and there are 100 points to a carat. Just like there are 100 cents to a dollar. A carat is equal to 1/5 of a gram and there are 142 carats to the ounce. Diamonds are so precious that they are weighed on scales whose delicate balance even a breath can tip!

The term carat comes from the carob tree, whose seeds were relatively uniform in weight. On ancient scales they weighed the same, with todays technologically advanced scales, we can only measure one three-thousandth 1/3000 of an ounce difference, between seeds!!