the four Cs
Diamonds are graded by their “four Cs” — Cut, Clarity, Colour and Carats (weight). Here’s a quick-fire explanation of each.
But first, an important ‘heads-up’
All four Cs are important in determining the cost of a particular diamond, and as you’ll find out, prices can vary wildly depending on how a diamond is classed within each.
That said, it’s important not to get too hung on the technicalities, especially when it comes to how a stone performs (rather than its size or weight).
Looks are pretty much everything
What really matters is how the diamond looks to you. Sometimes stones that don’t read so well can look great ‘in the flesh’. Conversely, stones that read well just don’t live up to expectation.
Sure, get to know what you’re paying for, but let your eye be the final judge.
Diamonds are cut with two things in mind …
- Keeping the most weight from the original rough stone; and
- Minimising the flaws and presenting the stone’s colour or “brilliance” best.
For diamonds (and gemstones too), the choice of cut is usually what will most enhance the value.
Diamonds are cut and polished to reflect light internally
The main facets of the pavilion (bottom of the diamond) are crucial to the finished look of the diamond and the angle of the cut is set by the specific gravity (density) of the stone.
Light coming in through the crown (or top) of the diamond gathers in the crown facets and bounces off the back pavilion facets and light is returned to the eye. If the facets are not aligned, there can be a loss of brilliance.
Claw settings aren’t a ‘must have’
This is why it’s okay to set diamonds in a rub-over or bezel setting. Despite common belief, you don’t need an open or claw setting to show off the brilliance of a diamond. (Some gemstones however do need light from more than one angle to best show their colour.)
Polish quality is important
The quality of the polish on facets is also important for the brightness of a diamond. Poorly polished facets will not allow enough light to go into the diamond or to reflect off facets. When polished and flat, they act like small mirrors, reflecting light back out to the eye.
Clarity refers to the visibility of flaws and impurities or inclusions (rather than their presence or absence). Inclusions are normal in most gem materials and often aren’t visible to the naked eye. Under high magnification many gemstones will show at least some microscopic inclusions. This can be useful to identify origin and separate naturals from synthetics. Generally, the fewer inclusions there are, the more valuable the stone.
Along with colour, clarity is one of the major criteria used in classifying diamonds. Usually, the more ‘clear’ the diamond, the higher its value. What this means is choosing a lower grade diamond may enable you to buy a bigger stone for the same money (the exception is for high value pink, red and blue diamonds. Their rarity forgives their clarity).
Buy diamonds based on how they look, not just how they read
Depending on the location of the flaws there may be no difference in the appearance of two stones even though one has a lower clarity rating. This is why it’s important to look at the diamonds you’re buying, not just read their specifications.
The best known gem grading system is from the Gemological Institute of America (GIA). Most of the diamonds we offer at EJA have GIA certification. Diamonds are graded under 10x magnification using a small magnifier called a loupe, usually table down (point facing up).
In the GIA system, there are 11 grades (from the top):
GIA clarity codes
|FL||Flawless: No loupe-visible flaws internally or externally|
|IF||Internally Flawless: No loupe-visible flaws internally|
|VVS¹||Very, Very Small inclusion or imperfection that is very difficult to see under a loupe|
|VS¹ VS²||Very Small inclusion or imperfection, difficult to see under a loupe|
|SI¹ SI²||Small Inclusion or imperfection easily seen with a loupe|
|I¹ I² I³||Imperfect (or included): Inclusions can be see with the naked eye|
Note: It’s very difficult for an untrained person to distinguish between an FL and an SI² diamond. It’s only when you get into the ‘I’ (or Piqué) grades that the imperfections start to become more visible.
The Scandinavian diamond nomenclature (Scan. D.N.) and other systems vary slightly in their classifications. The most obvious is in the I 1 to I 3 range where clarity is often referred to as P 1, P 2 and P 3 (where ‘P’ stands for Piqué — pronounced pee-kay). This is relevant for diamonds graded by HRD (Antwerp).
Position of the imperfection(s) in Piqué-grade diamonds
If your budget dictates that you must go for a lower-grade/clarity diamond, consider an ‘I’ or Piqué grade diamond with a well-placed inclusion.
If the imperfection is right on the edge of the girdle, then an inclusion could be covered by a claw or bezel when it’s set. In this case the diamond might look clear and you’ve got yourself a bargain.
Imperfections that are away from the girdle, somewhere in the middle of the stone will be visible. An unfortunately located inclusion can also block or bend light which in turn reduces the brilliance of the diamond.
4. Carat (weight)
Carat is the measure of weight of a diamond or gemstone. One standard metric carat is equal to 0.20 grams. Within a type of stone, it can also serve as an indication of physical size. For example, a 1.00 carat diamond will be physically bigger than a 0.8 carat diamond of the same cut.
You’ll also often hear the term ‘point’. There are 100 ‘points’ in 1 carat. A 10 point diamond, for example, is equivalent to 0.10 carats (or one-tenth of a carat).
Many perceive the prestige attached to owning a 1.0 carat diamond ring (or bigger). But how big is a 1.0 carat diamond? The following table will give you some idea of approximate physical size relative to weight.
Round cut diamond size guide:
|Diamond weight||Approximate diameter (mm)|
|2.00ct (200 point)||~8.2mm|
|1.50ct (150 point)||~7.4mm|
|1.00ct (100 point)||~6.5mm|
|0.75ct (75 point)||~5.9mm|
|0.50ct (50 point)||~5.2mm|
|0.25ct (25 point)||~4.1mm|
|0.10ct (10 point)||~3.0mm|
Note: This rule doesn’t flow across different types of gem material. Different gemstone materials have different densities (specific gravity). Hence a 1.00-carat sapphire will be a different physical size to a 1.00-carat diamond of the same cut.
Want to start designing the perfect ring?
If you’d like to start designing the perfect ring for your partner (or yourself), send us a quick email (preferred) or call us on 07 3379 2596 to have friendly chat about your options.