You may have already heard about or researched the 4 C's regarding diamonds:
Carat, Cut, Color , and Clarity.
In this post I will try to give a general overview of all of the important pieces of information to consider when buying a diamond.
The cumulative and relativity of these characteristics is what gives each diamond it's value or price per carat.
We will take each "C" one at a time.
Carat: is the weight of a diamond and recalls the days when diamonds were weighed in Middle Eastern marketplaces in comparison to the weight of one carob seed. One hundred seeds was a carat.
One carat is notated 1.00 ct. A quarter carat diamond would be 0.25 ct.
A common misconception is that carat refers to the "size " of a diamond. Two different diamonds of the same carat weight could conceivable be different sizes when considering the diameter of the stone from a top up view. The two stones could have different proportions and therefore weigh the same but look different face up. Also, certain cuts are heavier than others because the pavilions, girdles, tables, and crowns are of different proportions. This ties into the second "C"..
Cut: refers to the proportions in which the stone is cut, the symmetry and the finish. The best diamonds receive as much light at possible and refract and reflect it back out through the top of the crown and table facets.
This is done most efficiently when a diamond is cut with certain angles and proportions. Without getting too technical, the cut is graded on the relationship between the proportions in this diagram.
The cut also refers to the shape a diamond is cut in.
Certain diamond manufacturers have trademarked specific cutting techniques and styles. Certain details are created by some of these manufacturers more for marketing purposes and to drive up the profit margin on the stones. Some are specific to origin and have less of a bearing on quality as much as it does how it was sourced. Oval stones need to be purchased carefully, as often they are re-cut from less desirable stones that are originally larger stones of different shapes. For example, an oval could be cut from a larger round or marquise ( think pointy oval ) shape that has been damaged. If this re-cutting is not done properly, then the oval stone could have less desirable proportions. We want to search for a diamond that is a well cut oval that does not exhibit any of these signs. That is one of the reasons why it is wise to have a jeweler search for your stone rather than just a salesman.
In addition to proportions, the symmetry is also important. It is basically what it sounds like. The more even distribution of light comes from a stone that is symmetrical in cut.
The finish refers to the surface of the diamond. The polish of the surface, the roughness of the edge of the stone ( girdle), and the existence of any scratches from the cutting process remaining on the stone are all part of the finish.
The cumulative effects of the cut characteristics can be described in certain terms that identify the "sparkle" one hopes to find in a diamond. Diamonds with good to excellent cut can exhibit good brightness ( the amount of white light reflected out of the stone ), fire ( the amount of colored light reflected out of the stone) and scintillation ( the amount of contrast between lighter and darker facets of the diamond ).
Basically the overall cut of the stone is graded on the scale of : Poor , Fair , Good, Very Good, Excellent . Although a Fair stone may be useful in some jewelry designs, for the purposes of a quality piece of jewelry or engagement ring , we should be looking at Good through Excellent.
Color: refers to the natural color of a diamond. Every diamond has trace elements that form naturally along with the diamond. These elements contribute to the overall color of a diamond.
Color is quantified by alphabetic notation. The lower the letter of the alphabet, the more naturally white a diamond is. There is no A - C, the grading starts at "D " ( which would be a naturally white stone ) and continues through "K" as near colorless stones. After K-L stones begin to take on either brown or yellow tones. The more intense browns and yellows up the scale are graded as "fancy" and are more valuable than even colorless diamonds if also exhibiting unusual, intense colors. Some colored diamonds are enhanced by a process of high temperature and pressure ( referred to as HTTP ) that stabilizes and brings the natural color of a diamond forward.
Diamonds are graded by color in reference to "master stones" by a gemologist that is basically done by eye. For this reason , some color grading can vary slightly from one laboratory to another. For this reason, I like to consider color as a range . For example D-F are essentially extremely white, while most stones G-H are very white, challenging even experienced jewelers from telling the difference between them without special grading equipment. Even a J diamond with the right cut could look very nice in the right setting. The pricing difference between stones of equal size and other qualities but different color grades can be quite dramatic. For example a D color diamond could be thousands of dollars per carat more than a diamond with similar qualities in the GHI range when considering stones over 0.50 ct. I usually reserve D-F stones for smaller diamond choices for this reason, with the exception of step cuts ( Emerald and Asscher Cuts ). A slightly smaller stone with excellent cut and color will be far more dramatic than a larger stone that looks yellowish. Any color difference will be more obvious with adjacent stones, so we usually diamonds close together to be color matched. The color will be more important than the cut or clarity in the smaller diamonds.Color can also be a strong consideration in conjunction with metal choice. Yellow settings will require diamonds that are more white, which is one reason why you see a lot of diamond designs in white gold or platinum. When a yellow gold ring is desired it is still worthwhile to consider the diamond settings in white.
Clarity: refers to the amount, type , and configuration of the natural inclusions that occur in a diamond when it is forming. There are over 30 different inclusions that can occur naturally in a diamond or be created during the cutting process. Each one is classified and determined by a gemologist to effect the clarity grade by comparing the size, location, and interaction with other inclusions. It can get pretty complicated, but can easily be broken down into clarity grades which go follows:
I 1 and I 2: these stones have inclusions visible to the naked eye. They are best for smaller stones and are often seen in commercially made, mass produced jewelry. We typically don’t consider this grade for our projects.
SI 2: these stones have some inclusions that may be possible to see without magnification, but mostly a 10X loupe is needed to identify them.
SI 1: These inclusions are a little more difficult for a trained grader to see under 10X magnification
Very Slightly Included
VS2 - VS1: These inclusions are difficult for a trained grader to see under 10X magnification
Very Very Slightly Included
VVS1-VVS2: These inclusions are very difficult for a trained grader to discover and identify. Significantly more expensive than VS grade and very difficult to discern with even a trained eye. It can be an easy trap to "overpay" for a diamond in this category. The other three "C"'s of the diamond should be considered carefully when purchasing a diamond graded over VVS in clarity.
Flawless or Internally Flawless
IF - F : These stones are very rare and typically the most difficult to find and are usually much more costly per carat than even the best VVS1.
Basically, between SI2 and VS 1 is a good place to be when considering a larger diamond in respect to your "bang for your buck".
That said, some of these clarity grades can cross over slightly depending on which laboratory has done the grading.
The clarity grade is a cumulative assessment made by a gemologist considering the size, placement, and nature of the inclusions. There are several different types of inclusions and they are plotted or “mapped” on each diamond with very specific notations that are universally used by gemologists and jewelers. So as you can imagine, there is subjective humans involved , which means I like to inspect each diamond for it’s clarity grade vs. how it looks in the design myself.
Sometimes a diamond with a lower clarity grade may still be perfect for a certain design. For example, if a diamond has a noticeable inclusion on the outside edge, but is being used in a bezel set design with metal going all the way around the edge, then it may be a good choice for that ring.
There are basically a few different laboratories that grade diamonds. They all give the jeweler and consumer a certificate that makes the stone a Certified Diamond.
The GIA ( Gemological Institute of America) is probably the laboratory with the highest standards. Sometimes these diamonds also include a laser inscribed serial number or bar code on the girdle of the stone.
The AGL ( American Gemological Lab) is more known for grading colored stones, but does grade diamonds usually in accordance with the GIA standards.
The EGL ( European Gemological Lab) is a lab with locations in the US and many locations internationally. Their standards have come under scrutiny in recent years and I typically look at these diamonds with a much more critical eye.
There is competition between the laboratories and many different interests tied to each one ( The diamond business is about 75 billion a year), so there is a lot of stuff on the internet slamming each lab from a lot of different directions, so make sure to take note of the source of these articles.
Most insurance companies could care less where a stone is graded as long as it has a certificate. One also rarely hears anyone ask in conversation which lab graded their diamond. For these reasons I consider stones from various labs, and rely on my own experience in dealing with diamonds and education at the GIA to determine if the stones are accurate to the certificate. I've only had one noticeable discrepancy so far in years of looking at certified diamonds and it was a clerical error rather than grading mistake.
Also, all of dealers I buy from know that I insist on only natural diamonds that are not drilled, filled, coated, irradiated or otherwise treated ( You can occasionally find horror stories over these stones online). The diamonds I choose are also conflict-free, meeting United Nations Kimberly Process Specs. For more information on that: Kimberley Process
Metal choice: White metal makes diamonds look more white and is a good choice for most designs. 14K White Gold is .585 % gold and is slightly stiff and hard. It usually contains silver and nickel to give it the whiter color. The nickel can make white gold brittle and unpredictable which can translate into replacing prongs more frequently over the lifetime of the ring. 18K White gold is .750 % gold but contains less of the other trace metals and is therefore softer…which can also lead to bent prongs and wear over time. Platinum ( 95 % platinum / 5% iridium, ruthenium and other metals ) is very durable and hard, yet looks slightly more dull in appearance and is "colder" in look than white gold. It is also much more expensive.
My preferred white metal is 14K or 18K Palladium White gold. This metal has Palladium which is in the Platinum family of metals alloyed into the white gold to replace mostly the troublesome nickel. Palladium White Gold has a nice color, is easier to manipulate, wears very well, and is significantly less expensive than 950 Platinum. There are other nickel free alloys of white gold that have become more popular that I will use or suggest using for prong set designs. Bezel set designs or plain metal bands usually have no ill-effects regarding nickel in the alloy. For these designs, it is all about the preferred metal color.
If a Yellow or Rose gold ring design is preferred, then it may be worth considering a white gold or platinum setting for just the diamond depending on the natural color of the diamond and the overall design considerations.