Diamonds are normally graded and valued using the 4 C’s which are: Carat, Color, Clarity and Cut. In addition a 5th C has been added: Certificate, which is normally given to diamonds larger than 1 carat by GIA or HRD.
The following is designed to help clarify that the prices of diamonds are influenced by all 4 C’s and now also the 5th C for Certificate. If the stone has a certificate from GIA or HRD, it sure adds value, but you will rarely find it on stones under 1.01 ct.
Normally I will buy diamonds of the color H or I, with a clarity of VVS1 or VVS2, which has a cut grade of very good. This is where I feel there is the highest value for your money, without compromising on quality.
The weight of a diamond is measured in carats, which comes from the ancient use of the carob seeds being used to measure diamond weights. Luckily we have extremely accurate weights nowadays and we know exactly how much a stone weighs.
One carat is 0.2 gram, and the size of a diamond has a huge influence on the price. There are major break points in the price at 0.5 ct. 1.0 ct. 1.5 ct. 2.0 ct. etc. For example, diamonds with a carat weight of 0.99 ct. are much cheaper than a stone weighing 1.01 ct. The same is true in regards to the other break points.
A 1 carat brilliant diamond is approximately 6.5 mm in diameter
White diamonds are graded using a scale from D to Z where D is the whitest color possible with no traces of yellow. Z is the stone containing most yellow and after Z comes the fancy colored yellow stones.
The whitest stones are by far the most expensive and the price drops from there.
Normally I recommend diamonds in the color H, I or J because they are what we call ‘nearly white’. It is impossible to see any trace of yellow in them with the naked eye. H/I diamonds are generally really well priced and a good buy.
Clarity describes how many inclusions are found in the stone. Inclusions are impurities inside the diamond and blemishes are impurities on the surface of the stone. They could be polished away; however, that would reduce the carat weight.
GIA, which is the leader of diamond grading, uses these terms:
- F for flawless. There is no inclusions or blemishes under 10X magnification, observed by an experienced grader.
- IF, an internal flawless stone shows no inclusions when examined by an experienced grader using 10X magnification. It does – however – have some minor blemishes such as surface grain lines, naturals or extra facets. This can be removed by repolishing which is rarely done, as it is common to want to retain as much carat weight as possible .F and IF stones are extremely rare. You will hardly ever see one in a jewelry store.
- VVS1 and VVS2 are Very Very Slightly Included. These stones contain minute inclusions which are difficult even for experienced graders to see under 10X magnification. In VVS1, they are extremely difficult to see in the face-up view, or small and shallow enough to be removed by minor repolishing. In VVS2, they are very difficult to see. They might be pinpoints, tiny feathers, internal graining, a bearded girdle or tiny cavities.
- VS1 and VS2, Very slightly Included. VS diamonds contain small or minor inclusions observed with effort under 10X magnification. VS diamonds typically have small included crystals, small clouds, or small feathers.
- SI1 and SI2 Slightly Included. SI diamonds contain inclusions that are noticeable to an experienced grader under 10X magnification. Typically these are clouds, included crystals, knots, cavities and feathers.
- I1, I2, and I3, Included. Diamonds that fall in the I range contain inclusions which are obvious under 10X magnification. They might contain larger feathers or large included crystals. In some cases the inclusions affect transparency and brilliancy, and might even damage the stone.
Most of the diamonds you see in the finer retail stores are in the VVS to VS range.
Normally I recommend diamonds in the VS1 or VS2 range as the price in this range is very reasonable and the inclusions in the VS1 and VS2 stones are invisible to the naked eye. They are even difficult to see using a magnifier.
The cut of a stone is extremely important. Try to imagine that the uncut diamond resembles 2 pyramids on top of each other. This is where the cutters try to retain as much weight as possible. It is extremely important to cut the diamond perfectly in order to create the optimal reflection of light. The light has to be reflected off the sides inside the diamond and reflect back through to the top of the diamond to the viewer and not disappear into the stone.
To get the perfect brilliant cut, scientists have been arguing for decades, and there are few accepted cuts. At GIA they have decided that the diamond needs to have exact proportions to reflect light in the best way. When grading a diamond you take all the facets into consideration, and grade them in accordance to the weight and height of the stone.
Cut grades are Excellent, Very good, Good, Fair, and Poor. I would recommend stones which has a very good or excellent cut grade.
Asscher. A square cut similar to an emerald with facets; however, it is more square rather than rectangular shaped. Like the emerald, it has clipped corners. Recently the Asscher shape has become very popular.
Emerald. The shape still retains it's old world elegance.
Heart. Hard to find due to low demand, but some prefer a heart shaped diamond for sentimental reasons.
Marquise. Like the emerald, the marquise is a traditional shape. This is probably the fourth most popular behind the round, princess and oval.
Oval. Very popular for three stone anniversary rings, with two matching stones on the sides.
Pear. Mostly used in pendants, the pear shape diamond is shaped in a tear drop shape and has fairly good proportions to refract light well.
Princess. A square cut diamond that has refractive properties close to the round brilliant. The princess is one of the preferred square cut shapes.
Round. The Round Brilliant is by far the most popular and with its 57 facets it has the best angles to allow for for maximum brilliance.
A certificate or a diamond grading report is normally made for diamonds over 1,01 carat. It is used as a easy way to communicate information about the diamond, even if you do not have the diamond in your hand.
You will want to get a certificate from GIA or HRD which are the most well known diamond grading institutes.
Certificates from other companies can not be trusted the same way as they tend to grade the diamonds more positive.