One of the first things most men learn about when shopping for their first diamond is the “Four C’s”

Before saying anything more, let me emphasize that THE FOUR C’S ARE NOT WHAT DIAMONDS ARE ABOUT. Diamonds are 75% about what your girlfriend thinks of them and 25% what you, her friends, family, and co-workers think. There is no other utility to having a rock on her finger.

The diamond grading system was introduced in the mid 1900’s by GIA as a standardization of diamond quality. It was created to help jewelers purchase gemstones more easily. It has also become a marketing tool to help develop consumer confidence when purchasing diamonds.

If you are purchasing an engagement ring from a trustworthy retailer, you should not need to know about the four C’s - the retailer’s expertise in helping you choose the right diamond will cover the C’s and much more.

If you choose to purchase online or from a diamond dealer, knowledge of the four c’s is critical. With diamond dealers and online diamond retailers, the onus of choosing the right diamond is on the shopper. If you plan to purchase a diamond from me, you don’t need to read any of this.

For those of you who are just browsing, I’m organizing the diamond information in order of what I think is important to the average consumer. There’s what you should know:

Cost -
The unspoken “C” is by far the most important to nearly all shoppers. There are diamonds in every price range - you are the one who should choose how much you want to spend. Go to an online retailer, and narrow down the choices to “G VS2 excellent cut.” Look at the price ranges for different carat sizes. This should only be a benchmark to get you an idea of what diamonds cost. You can go up or down in price easily enough by varying the quality to fit your ideal size and budget.

Size -
The size of a diamond is usually measured in millimeters. For a round diamond, it will be the diameter. More specifically, a round diamond will be listed by the diameter at the longest and shortest points, and the height from culet to table. Approximate diamond sizes relative to carat weight:

8mm - 2ct
7mm - 1.4ct
6.4mm - 1 carat
6mm - .8ct
5.1mm - .5ct
4mm - .25ct

Tip: if you are interested in purchasing a diamond to put into a ring you are designing me, inquire about diamond size, not weight.

Carat -
A carat is a measurement of weight equal to one fifth of a gram. Wholesale diamonds & precious gemstones (like precious metals) are usually sold by weight. This means that a diamond dealer will assign a price/carat based on the quality of the stone. Jewelers can look at stones in a specific price/carat range, knowing that the quality of stones from a particular dealer will be similar in a comparable price/carat range.

There are more small diamonds than large ones, so the cost per carat increases with size. Diamonds are often priced in weight groups - say from .90 - .99ct - so there may be a price jump between .89 and .90ct even though the size difference is small. Finally, men tend towards certain numbers, so there is much more demand for diamonds 1 carat and just over than for diamonds just under 1 carat.

While there is a general correspondence between size and weight, it is not exact. Depending on the condition of the rough diamond presented to the cutter, diamonds can be cut shallow or deep. Very deep or shallow diamonds will generally not look as nice as a well cut diamond - although this does depend on the person viewing it.

Sapphires are generally cut deeper than diamonds, and will be a smaller size for the same carat weight. Even a diamond-cut sapphire (cut with the same proportions of a diamond) will be heavier because sapphire has higher density than does diamond.

Tip: when shopping from a...
Diamond Dealer: Tell them what you want to spend in price/carat, then tell them the carat weight.
Online: Online retailers often list the stock from many independent diamond dealers. You cannot expect similar quality in the same price/carat range because different dealers sell different kinds of diamonds in with different markups.

Shape -
Women care much more about diamond shape than men do. If you are a man purchasing a diamond as a surprise for a woman, please read about diamond shapes.

The most popular shape is round. There are many different cuts within each shape - many of which are proprietary. Far and away the most popular is the Round Brilliant. Old European Cut is an antique cut with fewer facets.

The shape of the diamond has a large effect on the design of the finished ring. Brilliant and modified brilliant cuts are more sparkly-blingy. Emerald cut is a little more elegant. Certain shapes look larger for the cost.

Read more about diamond shapes here, eventually.

Clarity -
This refers to how many imperfections are trapped inside the diamond. Small fractures and bits of other elements formed naturally inside each diamond as they were pushed through red hot magma to the earth’s crust. These imperfections - called inclusions - can make the diamond less beautiful. There are many types of inclusions - cloud, crystal, feather, needle, pinpoint, twinning wisp to name a few - some of which tend to look worse than others. Also, it matters where in the diamond an inclusion is.

The clarity scale - clearly developed by Harvard’s best - reads as follows:

I3 - Included (worst)
I2 - Included (worse)
I1 - Included
SI2 - Slightly Included
SI1 - Slightly Included (better)
VS2 - Very Slightly Included
VS1 - Very Slightly Included (better)
VVS2 - Very VERY Slightly Included
VVS1 - Very VERY Slightly Included (better)
IF - Internally Flawless
FL - Flawless

What it means in real terms:

I - Looks like crap. Don’t purchase an included diamond unless you lost a bet.
SI - Slight inclusions that you may be able to see if you are looking closely. Good if you’re on a budget or to put into less scrutinized jewelry such as earrings.
VS - Eye clean, with slight inclusions if you’re looking under a 10x loupe. Adequate for 95% of people.
VVS - Slight inclusions if you’re looking under a 100x microscope. Good if your girlfriend works in the industry or has higher expectations than 95% of people.
IF - No visible inclusions at 100x magnification. Good if your budget is high but you don’t want a larger stone.

Once you have found a clarity that works for you, stop there. Improved clarity will not improve the way a diamond looks. It will only affect how you think about it, as well as it’s potential resale value.

Tip: Do not buy heavily included diamonds unless the inclusions look exactly like your GF’s birthmarks or favorite constellation. Poor clarity will trump all the other C’s to make a diamond look terrible.

Color
Diamond color (in the context of the four “C’s”) refers, ideally, to the lack of color in a stone. While the scale goes from D to Z, I recommend considering only D-L.

D - Colorless - the highest, most expensive rating.
E - “Colorless,” but less so than D.
F - Still colorless, but less so than E.
G - “Near Colorless,” often with a tinge of yellow. Popular color with my clients.
H - Still near colorless, and less expensive than G.
I - Guess what? Near colorless. I color diamonds start to look dark, but still great.
J - A little yellow (usually). These start getting much less expensive, since the color is visible to more people. I recommend setting J color diamonds in yellow gold to offset the color.
K, L, M - obvious color. Can look good if color is part of the design. If color is brown instead of yellow, these can be really cool in the right setting. Much less expensive.

Unlike clarity, diamonds tend to look continuously better as you travel up the scale.

Tip: Diamond color only matters when your diamond is clean. Once there is enough moisturizer and fried chicken stuck to the bottom of your diamond, no one will know what color it is. Clean the underside of your diamond with a toothbrush and any household cleanser to bring back the brilliance.

Cut -
In the context of the four “C’s,” cut refers to how well the diamond is cut, rather than the shape. Remember that the gradings are based on measurements and variations from certain guidelines. “Ideal Cut” is the name of a round brilliant cut developed by Marcel Tolkowsky. Most people will agree that ideal cut diamonds look great. However, some of you will like slightly deep or shallow diamonds. Beauty is in the eyes of the beholder.

Many people under-appreciate the importance of cut - probably because it is not possible to fully understand cut quality as a novice buyer. However, you can close your eyes and trust GIA when they rate diamond cuts:

Poor - the diamond will look mediocre
Fair - the diamond will look average
Good - the diamond will look good
Excellent - the diamond will look excellent
Ideal - the diamond will look excellent, and cost more.

A lot of online vendors use slightly different terms. These variations are called “marketing," and mean very little. Most men will opt for Good and Excellent when looking at the above options. However, add an extra rating, such as “Signature Ideal,” and more men will purchase “excellent” diamonds.

Cut is graded for round brilliant diamonds in GIA lab reports, however, not all diamond shapes are graded for cut.

Congratulations! You’ve gotten through the “four C’s.” The most important diamond specifications are behind you. If you are still awake, there is more.

More options-

Polish-
This refers to how well the facets were cut. The edges of each facet should be very crisp. Sometimes, if the cutter slipped or used a dull cutting tool, the edges will be less crisp. Also, used diamonds may have small chips in the facets from wear.

Symmetry-
Refers to exactly this - how symmetrical in size and position is each of the facets. An asymmetrical stone will not necessarily look less brilliant - just less symmetrical.

Fluorescence -
Clarity is graded based on a 100x microscope. However, there are plenty of inclusions that are too small to see even at 100x. When there are many of those tiny inclusions made up of a substance with fluorescence, they will glow under long-wave UV light. Depending on the inclusions , it may glow in different colors. Blue is most common, but occasionally, one gets pink or green fluorescence.

Strong fluorescence can look milky - especially in bright light. Fluorescence will make the diamond look slightly worse, but it will not be particularly noticeable to most people. Since most diamonds do not display fluorescence, it’s presence will lower the cost of a diamond in an outsized proportion to the quality of its appearance. Fluorescence is actually a good characteristic for shoppers on a budget.

Girdle-
The girdle is the edge of the diamond at its widest point. It is the stone just around the girdle that is set into the metal prongs or bezel of a ring.

A thick bezel means that you are paying for extra carat weight in the widest part of the diamond, without realizing a proportional increase in size. It is also a little more difficult to set into a ring.

A very thin girdle makes for a larger stone that will chip easily.

A girdle that is very uneven will be difficult to set straight.

Girdles are sometimes faceted - this doesn’t much matter. They are sometimes laser-inscribed. This will give you piece-of-mind that you are getting the diamond that is described in your diamond certificate.

Culet - The bottom of the stone usually comes to a point in the modern brilliant cut. When stones do not come to a point, the flat bottom of the stone is called a culet. Antique stones tend to have culets, which will be reflected multiple times throughout the facets of the diamond. For large culets, this can degrade the brilliance and appearance of the diamond.

Proportions -
Diamonds are measured not only in size, but in angles. This tells you a little more about how the diamond was cut.

Table % - the proportional length of the table (the flat facet on the top of the diamond) as compared to the total diameter.

Depth % - the distance from table to culet as compared to the width.

Pavillion Depth % - the perpendicular distance from the girdle plane to the culet.

Crown Height %- the perpendicular distance from the girdle plane to the table.