Learn About Diamonds – A Beginner’s Guide
If you are looking to buy a Diamond or just looking to learn more about these amazing gemstones, then you have clicked on the right link.
In this guide, I am going to break down what you need to know about Diamonds, including:
So that you will have a much better understanding of one of the most important gemstones in history.
But who am I? My name is Paul Haywood FGA DGA, I’m a qualified Gemmologist and Diamond Grader through the Gemmological Association of Great Britain and have taught Diamond Grading in the past, so I do know a thing or two about Diamonds, so let’s get started…
Natural and Synthetic Diamonds
Let’s start with one of the biggest changes to the world of Diamonds in the last few years, the introduction of Synthetic (more commonly known as lab-grown) Diamonds.
I won’t go too deep into this section but the important things you need to know about Synthetics vs Natural Diamonds includes:
One thing I’m not going to cover in this guide is the environmental or ethical aspects but if you are interested in that, I have covered this in a lot more detail in my Lab-Grown vs Natural Diamonds post.
What Are The 4 C’s of Diamonds?
The 4 C’s stand for:
Which are the four main quality factors by which a Diamond’s quality is assessed and these quality factors also play a big part in a Diamond’s price as the better the quality of the Diamond, the more it is worth.
The 4 C’s – Colour
The first of the 4 C’s is colour and when we are talking about colour in Diamonds, there are two main categories:
1: Colourless Diamonds
Colourless Diamonds are by far the most common, with an estimated 98% of all Natural Diamonds falling into this category.
However, not all ‘colourless’ Diamonds are actually colourless. Many have a hint of colour, this is most commonly yellow but brown and grey can also be seen.
To assess the quality of a colourless Diamond, we grade it on how free from colour the stone is, with stones with less colour being given a higher colour grade.
When grading the colour of a Diamond, we look through the pavilion of the stone, with the table face down (like the stone in the picture) using controlled light, such as a daylight lamp, with the stone in a grading tray (a piece of folded card).
This allows us to see the true body colour of the stone.
The most commonly used grading chart is the GIA’s, which was developed in the 1950s and ranges from D (colourless) to Z (light tint).
While the chart above is useful, it doesn’t tell the full story when it comes to colour in Diamonds and some useful things to know include:
2: Fancy Colour Diamonds
The other 2% of Diamonds are known as fancy colour Diamonds and for a Diamond to fall into this category, it needs to:
- Possess a rare colour such as Red, Blue or Pink
- For Yellows and Browns, the colour must be stronger than a Z colour on the grading scale mentioned above
The method for grading fancy colour Diamonds is different as the stone is assessed on these three factors:
1: Hue – The Body Colour Of The Stone
Pure colours are the most desirable but many stones will have a second or possibly third hue, when described, the main body colour of the stone will be last, with the hue before it, for example an Orangey Pink Diamond is a mainly pink stone with a hint of orange.
2: Saturation – How Intense The Colour Is
The second is saturation, which is how intense the colour of the stone is.
3: Tone – How Light Or Dark The Stone Is
The third is tone, which is how light or dark the stone is. Tone is combined with Saturation to describe the stone, which is where you will see descriptions like Fancy Light, Fancy Vivid or Fancy Dark
There are some Faint, Very Light and Light Diamonds where it can be difficult to see the colour, such as a Very Light Blue Diamond that I once looked at and if I hadn’t seen the report, I would have said it was colourless.
The 4 C’s – Clarity
The second of the 4 C’s is Clarity and the clarity of a Diamond is graded on how free the Diamond is from inclusions, with some people referring to this as how ‘clean’ the stone is.
If you aren’t sure what an inclusion is, it is basically an imperfection within the Diamond and can include things such as:
- Crystal inclusions – this is where there is a small crystal within the stone, this can be another Diamond or other gemstones that form in similar conditions such as Garnet
- Clouds – these are a number of small inclusions, usually very small crystals that are grouped together within the Diamond
- Fracture – this is a non-directional breakage within the Diamond
- Cleavage plane – this is a direction breakage within the Diamond (only found in I clarity Diamonds)
When it comes to grading the clarity of Diamond, the most commonly used grading chart is the one that was developed by the GIA and includes the following grades:
And these grades are assigned by viewing the stone under 10x magnification, with inclusions visible through the top of the stone having a bigger impact than ones that can be seen through the pavilion.
As you can see in the image above, the VVS, VS and SI have two subcategories for each but why is this?
The official answer to this is that the size and location of the inclusions is a deciding factor but this doesn’t really explain it in my opinion and from experience, the difference a 1 and 2 is:
- The inclusions for a 1 are generally located under the crown facets, making them more difficult to see
- The inclusions for a 2 a generally more central and usually under the table, which makes them easier to see
For the I clarity grade, you will see that there are three subcategories but the reasons for these are different to the ones mentioned above as:
- I1 Clarity Diamonds have inclusions that impact the beauty of the stone
- I2 Clarity Diamonds have inclusions that notable impact the beauty or affect the durability of the stone
- I3 Clarity Diamonds have inclusions that impact the beauty and durability of the stone
I always recommend avoiding I Clarity Diamonds due to the looks and/or durability of the diamond being affected and instead, go for an SI1 or better.
The 4 C’s – Cut
Cut is arguably the most misunderstood of the 4 C’s as there are many people that think that Cut is the style of cut, such as Round Brilliant or Princess but what it actually is, is the quality of the cut and it is arguably the most important of the 4 C’s.
This is because the quality of the cut has a big impact on how the stone looks, with well-cut Diamonds having lots of life and sparkle and poorly cut stones looking dull and lifeless.
But what factors affect the quality of the cut, well there are three main things:
1. Proportions
This is the most important of the three elements as these are basically the dimensions of the Diamond and includes:
- Table width
- Crown angle
- Crown depth
- Pavilion angle
- Pavilion depth
- Total depth
- Girdle thickness
- Culet size
- Star facet length
- Pavilion facet length
For each of these 10 factors, there are a range of parameters, which means that two Diamonds can have the same cut grade but different proportions and can result in the stones looking a little different.
Currently, only Round Brilliant Cut Diamonds have a set of ‘ideal’ proportions and are the only style of Diamond that is assigned a cut grade by the GIA.
2. Symmetry
The second factor is symmetry and this is broken down into two categories:
- Proportional Symmetry – this is things like if the table is centered, the girdle is even all the way round and angles are the same on all sides
- Facet Symmetry – this is basically do the facets on one side look the same as the other and includes things such as extra facets or facet edges not meeting properly
Basically drawing an imaginary line down the middle of the stone and seeing if one side looks the same as the other.
Some differences in proportional symmetry can affect how the stone looks as slight changes to angles etc can affect how light interacts with the Diamond.
3. Polish
This is the quality of the final polish as not all Diamonds are finished to the same standard and stones with a lower quality final polish may have:
- Polishing lines of facet faces
- Burn marks on the surface of the Diamond
- Unpolished areas, either from the original crystal or earlier polishing stages
Some small polishing imperfections will only be noticeable under 10x magnification.
As I said above, currently only Round Brilliant Cut Diamonds are given a Cut grade and each of these three factors are individually graded from one of five grades:
- Excellent
- Very Good
- Good
- Fair
- Poor
Diamonds that get an excellent grade across all the factors are sometimes referred to as Triple X stones and generally attract a higher premium.
The 4 C’s – Carat
The last of the 4 C’s is Carat and this is weight, not the size of the Diamond.
This is the universal weight measurement for Diamonds and Gemstones and 1 carat is the equivalent of 0.2 grams.
Carat also plays a big part in a Diamond’s value, just like three other C’s but Diamonds are sold by their weight, with each stone having a price per carat and with all other factors being equal, it is the carat weight that will have the biggest impact on a Diamonds value.
There are certain thresholds that can cause a big increase in a Diamonds price, these are most notable at round numbers such as 1, 2 or 5 carats, for example:
This not only applies to buying a Diamond but also when selling one as well as stones over these thresholds are much easier to sell.
Also be sure to know the difference between total carat weight, often displayed as TCW and the weight of the main stone. If the stone is set with lots of small diamonds, they may advertise the TCW as 1 carat but the main stone may weigh less than half a carat.
What Is The Most Important Of The 4 C’s?
While all of the 4 C’s are important, Cut is arguably the most important as this has a big impact on the look of the Diamond, followed by Clarity, Colour and Carat.
But when it comes to buying a Diamond, you should look to get the best balance of the 4 C’s and unless you have a budget to buy the very best, the best balance can be found in:
- A Colour Grade of F, G or H – as these are all colourless when viewed through the top of stone
- A Clarity Grade of VS1 – SI1 – as you won’t be able to see the inclusions in a VS1 or VS2 and the inclusions are generally under the crown facets on an SI1 and depending on their location can be hidden by the setting
- A Cut Grade of Excellent or Very Good – some diamonds with a Good cut can look really good but I generally recommend going for higher cut grades
As for Carat, this will all depend on your budget but a lot of the Diamond buying process comes down to your own personal preference and when it comes to buying your perfect Diamond, buy what YOU like!
Not what the salesperson says is the best or what other people like, you will be the one wearing it so make sure you like it before spending your hard-earned money.
Fluorescence
Fluorescence in a Diamond is something that is misunderstood as there are many people (including people who work in the industry) who believe that having any kind of fluorescence in a Diamond is a bad thing.
But in the majority of Diamonds, fluorescence has no notable impact on the look of the Diamond and without shining a UV light on the stone, you probably wouldn’t have any idea whether the stone has fluorescence or not.
The only time that fluorescence is a negative is when it impacts on the beauty of the Diamond and this sometimes happens in some Diamonds with very strong fluorescence as it can give the stone a milky appearance.
Styles of Diamond Cuts
I covered cut quality above, so let’s have a bit of a look at the different styles of cut that are popular for Diamonds and while there are quite a few, the majority fall into 1 of 2 categories:
Brilliant Cuts
The majority of Diamonds are cut as brilliant cuts, which are cuts where the pavilion facets have been designed in a way to return the maximum amount of light to the person looking at the stone and when this light passes back through the crown facets, it produces that fire and brilliance (sparkle) that Diamonds are known for.
The original, most researched and by far the most popular style of cut is the Modern Round Brilliant, with other shapes that have a brilliant style pavilion facet arrangement being known as modified brilliant cuts and these include:
One thing with elongated brilliant cuts, like the Oval, Pear and Marquise is that they can suffer from what is known as the ‘Bow-tie effect’, which is where pavilion facets can appear dark due to the way some stones have been cut.
Step Cuts
The second most popular category of Diamond cuts are the step cuts, which includes:
Step cuts don’t possess the same fire and brilliance as brilliant cut stones due to the styling of the pavilion facets but usually have very good clarity as inclusions are a lot easier to see than in brilliant cuts.
Treatments
Another quality factor to consider is whether or not the Diamond has been treated as this can have a big impact on the value of the stone as untreated Diamonds are worth considerably more!
But how are Diamonds treated?
Clarity Treatments
Some lower-quality Diamonds with very obvious inclusions are treated to try and reduce the appearance of these inclusions and while the stone may look better to the naked eye, they don’t improve the stone’s clarity grade.
With the rise of synthetic Diamonds, treated stones are becoming less common in the marketplace as they were aimed at the lower end of the market, which is where synthetics are now the go-to choice for many.
Fracture Filling
Fracture filling is a process where they fill any surface-reaching fractures with a high lead content glass, which has a similar refractive index to Diamond and makes the fractures less visible to the naked eye.
The problem is that fracture filling is not a permanent treatment, as the glass can be removed from the stone, which is why reputable gem labs don’t give fracture-filled Diamonds a clarity grade
Laser Drilling
Laser drilling is a process that removes dark inclusions from a Diamond and is done by using a laser to drill down to the inclusion it is then either burnt away or bleached, resulting in a much lighter inclusion that is less visible.
The problem is that this treatment adds another inclusion in the form of the laser drill channel but as this treatment is permanent, laser-drilled Diamonds are usually given a clarity grade but it is usually an I grade
On some occasions, both treatments can be done to a Diamond.
Colour Treatments
Something that has become more common over the last few years is colour-treated Diamonds, with two of the most popular ways of doing this being:
High Pressure High Temperature (HPHT)
This treatment is often done to natural brown diamonds as the treatment fixes the cause of the brown colour and in many cases, the Diamond will be completely colourless after being treated and the colour change is permanent
Irradiation and Annealing
These treatments are done to create fancy colour diamonds, so if you are planning on choosing a pink, blue or orange then always check the diamond report to see if the colour is natural.
The process involves the diamond first being exposed to radiation which alters the colour, commonly to green but also bluish greens and black. If another colour is desired, then the stone may subsequently be heated to between 500°C and 1200°C to produce yellows, oranges, browns and pinks
But don’t worry, irradiated Diamonds aren’t radioactive once they have been treated.
Treated Diamonds usually cost less than untreated ones but there is good reason for this as there is less demand for them and they can be difficult to resell, which is why I always recommend buying untreated Diamonds, especially for engagement rings.
Lab Reports (Certificates)
While they are often referred to as certificates, the correct terminology is a lab report and it is an important document as they can contain a lot of information about the Diamond, including:
- Colour
- Clarity
- Cut
- Carat
- Dimensions
- Origin (mined or lab-grown)
- Any treatments
- Fluorescence
And I always recommend buying a Diamond that comes with a report from a reputable gem lab such as the GIA, Gubelin, IGI or HRD as they all have high standards for their Diamond grading and all their staff are experienced, qualified gemmologists.
But it should be noted that Diamond reports are the opinions of the people who grade the stones and are not facts, which is why they are reports and not certificates.
This is also why if you see the document accompanying a Diamond saying certificate or certificate of authenticity, then you should run away from that stone as quickly as possible!
Want to Learn More?
I’ve created a short online video course that covers the basics of Diamond Grading in more detail.
Other posts from The Gem Guide series:
I'm Paul Haywood FGA DGA, the owner and founder of Haywoods Gems, I'm a fully qualified Gemmologist and Diamond Grader from the Gemmological Association of Great Britain.
