The 5 Cs of a diamond

Carat Weight 

It is a common misconception that carats refer to the size of a diamond. In reality, a carat is the standard unit of weight by which diamonds are measured. One carat equals 200 milligrams or 0.2 grams.

Carats are also expressed as points, with one carat equaling 100 points. So a one carat diamond is also referred to as a 100 point diamond.

Large diamonds are far rare than smaller ones. Hundreds of tons of ore may have to be processed to extract a single, gem quality, one carat diamond. So the price of a 100 point diamond is always more than two fifty point diamonds, or four 25 point ones.

Since a carat is a measure of weight, not size, one diamond of the same carat weight may look bigger than another depending on the cut. A premium cut Canadian diamond may actually appear bigger than many diamonds of a higher carat weight.

A diamond’s cut is what gives the diamond its critical brilliance and sparkle. If you are simply shopping for the largest diamond, you could end up with a gem of such inferior quality that it looks just like glass.  The difference between a good cut and a poor cut diamond can be really astonishing. That is why you need to consider the other 3 Cs of a diamond – most importantly, the Cut.

Cut

The cut of a diamond is probably the most important of the four Cs and the only element that can be affected by human intervention. It is also the most challenging of the 4 Cs to grasp.

The brilliance of a diamond depends almost exclusively on its cut. A good cut gives a diamond such fire that the brightness seems to emanate from its very heart.

A diamond cutter needs to position each of the stone’s facets or sides in specific geometric alignment to achieve the maximum reflection of light that causes a diamond to sparkle.

Now, here is a caveat. Cut must not be confused with shape. Shape refers to the outward appearance of a diamond. It may be round, square, oval, marquise, emerald, or pear shaped. Cut refers to the reflective qualities of a diamond, not its shape.

When a diamond is cut beautifully, light enters through the table (top surface), travels to the pavilion where it gets reflected from side to side, before totally internally reflecting back out of the diamond through the table. This light causes the scintillating fire-and-dazzle effect of a diamond to the observer’s eye.

When a diamond is not cut well, a part of the light entering through the table could, on reaching the facets, dissipate through the sides or bottom of the stone rather than reflecting back to the viewer. If it is cut too deep, light is lost through the sides whereas if it is cut too shallow, light leaks out through the bottom of the stone. Less light reflected back naturally means less brilliance.

Gemologists will tell you that the best cut diamonds follow a set of formulae designed to bring out the greatest amount of sparkle in a diamond. These formulae concern the proportions of a diamond – for example those between the depth and the diameter, or between the table diameter and the stone diameter.

There are several grading methods to help customers identify the cut of a diamond. For example: –

Ideal:	Intended to maximize brilliance in round diamonds, this cut disperses the     ‘fire’ magnificently. For the discerning customer, the finest thing money can buy.
Premium:	Though slightly less expensive, a premium cut round diamond can give many    ideal cut diamonds a run for their money. This cut too maximizes brilliance.
Very Good:	These diamonds reflect most of the light entering them. Here the cutter has traded    off some sparkle for a larger size. Priced slightly below premium cut diamonds.
Good:	These diamonds reflect much of the light entering them, their proportions outside    the preferred range in order to create the largest possible diamond from the rough crystal. Provides cost saving to customers without sacrificing quality.
Fair/Poor:	Such a diamond reflects a small portion of the light entering it. Cut to maximize    carat weight, these are typically found in retail mall jewellery stores.

Colour

An overwhelming ratio of diamonds is yellow, brown and even black in colour. Most of them find their way into industrial use. The ‘white’ or colourless diamonds are the rarest. Since they allow more light to pass through them and therefore produce more ‘fire,’ the whiter a diamond’s colour, the grater is its value.

The Gemological Institute of America grades colour of diamonds alphabetically from D (totally colourless) to Z (yellow). Diamonds D to F are considered ‘colourless’, G to J ‘near colourless’, K to M ‘slightly tinted’, N to R ‘very light yellow or brown,’ and S to Z ‘light yellow or brown’.

However, the D – Z scale being continuous, difference between an F and a G is miniscule. Engagement diamonds are usually in the colour range G to H.

Breslauer & Warren can help you make comparisons for grading. An un-mounted diamond has to be placed face down on a white piece of paper next to a master set of stones graded by the Gemological Institute of America. You can compare the colour of the diamond with stones in the reference set until you get the best match.

One small tip here: choice of stone could depend on the setting you want. Yellow gold is more forgiving to a less than colourless diamond.  But if you mount your diamond on platinum or white gold, its colour should be in the D – G range.

Clarity

Most diamonds have some identifying characteristics or inclusions called ‘flaws’ on or within them. Flaws are usually inherent properties of the mother stone that occur due to the fantastic amount of pressure during its formation. A few flaws may however result from the harsh conditions during the cutting process.

A diamond’s clarity is determined by the visibility, number and size of blemishes it contains. The lesser the number of inclusions, the clearer and more brilliant the diamond, and therefore more highly prized. Diamonds with little or no flaws are highly valued not just for their beauty but also because they are extremely rare.

There are various types of flaws that occur in a diamond.

Pinpoints:	Very small white dot on surface – easily the most common flaw.
Carbons:	Very small black dot on surface – slightly less common than pinpoints.
Feathers:	Small cracks looking like cracks in glass. Small feathers are harmless, but large feathers can grow as the diamond ages.
Clouds:	Hazy internal patches made up of miniscule crystals.
Crystal Growths:	Crystalline growths inside a diamond, looking like a diamond in a diamond.

A diamond’s clarity is graded under 10X loupe (a strong jewelry magnifying glass) magnification into various clarity grades: – 

FL:	Completely flawless.
IF:	Internally flawless; further polishing can remove external flaws which are present in the stone.
VVS1 - VVS2:	Very Very Slightly included. Flaws can only be detected with a 10X microscope by an expert.  If a flaw is visible from the top of the diamond, it is a VVS2.  If flaws can only be detected when viewing from the bottom, then it is a VVS1
VS1 - VS2:	Very Slightly included. Flaws are visible with a 10X microscope, but it takes a long time (more than about 10 seconds) to see them.
SI1 - SI2:	Slightly included. Flaws are visible with a 10X microscope
I1 - I3:	Included. You can see flaws with the naked eye.  I2-I3 diamonds are best avoided.

To many people, clarity is the least important of the 4 Cs when purchasing their diamonds.  The reason is very simple. The recipient or her friends are highly unlikely to pull out a 10X microscope to examine the flaws on the diamond! For grades IF through SI, a diamond's clarity grade has an impact on the diamond's value due to the rarity factor, not on the unmagnified diamond's beauty.

A diamond can have flaws and still look stunning. Diamonds with VVS and VS grades are excellent choices for both value and appearance. More affordable (and still exquisite) are diamonds in the SI1 and SI2 grades which gemologists call "eye-clean" - diamonds with no flaws visible to the naked eye. If you still have reservations, you can opt for diamonds with clarity grades of VS2 and higher to ensure a truly eye clean diamond.

A word of caution here: if you're buying an emerald cut (or any other step cut) diamond, it is safer to buy a diamond with clarity greater than SI1 because clarity flaws are more easily visible in step cuts.

Unfortunately, clarity is very difficult to judge accurately by an inexperienced consumer. Detecting flaws needs a lot of practice. Breslauer & Warren will however spend the time you need to get comfortable with the clarity of your stone.
Apart from the traditional Four Cs of a diamond, there is a modern-day “Fifth C” – which stands for CERTIFICATION.

Certificate 

Diamond certification, also called a grading report, is a complete evaluation of a diamond performed by a qualified professional with the help of specified gemological instruments. Each recognizable, individual characteristic of a diamond is listed on the certificate.
 
There are 4 major international laboratories in North America that grade, certify and sometimes estimate market value of diamonds.

They are:

AGS – American Gem Society
EGL - European Gemological Laboratory
GIA - Gemological Institute of America
IGI - International Gemological Institute

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