The Practical "Dummies" Guide to Buying Diamonds - The Four Cs and More!-Isle of Her

The Practical "Dummies" Guide to Buying Diamonds - The Four Cs and More!

For most people that aren't in the business of buying diamonds regularly or that are you know, billionaires - buying diamonds has always been a bit of a minefield (ha, you see what we did there? ;)) 
If we're honest, most jewellers usually seem happy to keep it that way because it helps to keep the "allure" alive.  But, we expect that if you've made it here, you've already come across and read a tonne of articles talking about the "The Four Cs", without fully understanding what it means for you.

The truth is, whether it's an engagement ring you're looking for, a wedding band, or even a pair of solitaire earrings, it doesn't have to be a 'minefield' to make a smart decision. 
Each of the Four C's plays a crucial role in itself, but it's the combination of each that ultimately makes the stone you choose uniquely rare to just you. The beauty is - YOU get to pick that combination based on what's most important to you (whether it's your budget, size of the stone or the quality of the stone) and the priority each of the other factors take. The goal, at the end of the day, should always be to get the most value for what you are willing to pay.
Packed with practical advice on buying a diamond or diamond jewellery, this post should helpfully steer you in the right direction and arm you with more practical tips on how to make a decision, but get in touch with any questions (Email, Live Chat, DM us on Instagram - whatever works) and we can walk you through each factor in a lot more detail (or a lot less, if that helps!) to help you make an informed decision. 
Buying diamonds should always feel like a special experience, whether it's for yourself or for someone special!

"The Four Cs"

So, the four words that you need to remember when shopping around for a diamond are: CUT, COLOUR, CARAT and CLARITY!
The key is to think of them as individual 'Levers' on a machine, where each dimension can be adjusted up or down to get you to the perfect combination and stone for you. Tweaking each lever even slightly can have a massive impact on the price you pay for a stone, but understanding your key priorities goes a long way to helping you find the right balance between each:
  1. Your Budget: Usually the biggest driving force for many, having a rough budget in mind can help to to narrow down your options before you get overwhelmed or too caught up in the details
  2. Size: Having an approximate size in mind (even if it feels a bit ambitious to start with) helps baseline your lever setting
  3. Your Priority: There's no shame either way, but think about what matters most - does size matter most to you, or does quality? Leaning one way or another will naturally drive you to shift levers to fit your goals. 
Isle of Her Practical Diamond Buying Guide 4Cs explained


When considering the 4 C's, it helps to start with Carat, because it naturally sets a minimum threshold for the other 3 C's. It's simple - the larger the stone, the more visible it is to the naked eye, and therefore demands a minimum threshold of clarity and cut. 
It's important to remember that when we talk about the carat of a diamond, it refers to the weight and not the size of the rock on your hand. Diamonds are measured in 'points'. 100 points equals to 1 carat ("cts").  Without a doubt, a bigger stone does symbolise grandeur and royalty - think about Kim Kardashian West's engagement ring which was approximately 15cts and is worth about $4 Million! - however, the carat weight should never be the only factor in deciding which diamond to buy. 
Isle of Her 4Cs Guide Carat Weight Scale
The carat does not solely determine the sparkle - the cut is what really gives the diamond its true beauty. A well-cut, lower carat diamond can appear larger than a huge poorly cut one and it will cost a lot less. To a human eye the difference between a 1.1 carat and a 1.2 is fairly impossible to tell apart, yet the cost between the two maybe fairly significant.

Isle of Her Tips & Tricks! 

  • Rounded carat sizes (i.e. 0.50ct, 1ct, 1.5cts) tend to be extremely popular, and therefore more expensive.
  • Choosing a marginally higher or lower carat weight (e.g. 0.48ct, 1.01ct, 1.52ct) can get you a much better deal for your money - We promise, you won't be able to tell the difference and you can always round it up in your head if it helps!
  • If you're buying an engagement ring:
    • DO NOT let anyone tell you how much you should or should not be spending on an engagement ring! The 3 month salary guide is a marketing ploy and has no bearing on how much you love or cherish your partner. That's an absolute Isle of Her No-No!
    • In spite of the unstoppable memes - bigger isn't always better. Think of your/your partner's style and taste and tailor the design and stone to what they would love. 
    • If size is important, "Fancy cuts" such as a Heart, Oval or Pear shaped diamond are usually less expensive and can appear larger than a Round stone even at the same carat weight


Often overlooked, the Cut of the diamond has the greatest influence on the diamond's beauty and sparkle, given that the cut is what unleashes its light. Generally the cut is assumed to be the shape of the diamond - Round, Oval, Heart, Princess and so on - but in reality the cut determines how the diamond interacts with light and has a massive impact on how brilliant and sparkly it will appear. 
When originally mined, raw cut diamonds do not look like much at all. It's the craftsmanship of a skilled cutter that shapes these gems into beautiful detailed stones. So, it doesn't matter if the diamond is 1ct, 3 cts or 10cts - it will look dull if it’s inner light is being sent elsewhere by a poor cut!
The cut grading is measured on a scale of 5 categories
  • Excellent: The diamond has an even pattern of bright and dark areas [Recommended, of course]
  • Very Good: The diamond is bright and polished, there may be some increased darkness [Recommended]
  • Good: A more limited grade with dark areas [Not recommended unless it's a smaller stone]
  • Fair: There’s a lack of contrast when your diamond is face up [Not Recommended]
  • Poor: The diamond’s diameter makes it appear smaller than the carat indicates [Nope, never]
Isle of Her 4Cs Guide Cut Grading Scale

Isle of Her Tips & Tricks!

  • "Fancy cuts" such as a Heart, Oval or Pear shaped diamond are usually less expensive and can appear larger than a Round stone, even at the same carat weight
  • The bigger your stone (0.7cts or above), the higher your cut grading should be (i.e. Excellent or Very Good at a minimum)


The clarity of a diamond really speaks to the 'Quality' of the stone. Natural diamonds are mined from the Earth and Mother Nature, and form under enormous pressure and heat - so it's only natural for them to have 'flaws' or marks within the diamond. 
An important point to note - these 'flaws' are actually what gives your diamond its character and makes it unique. Also, a diamonds beauty is not just determined by its clarity, as majority of the marks will not be visible to you or me and can only be seen under a 10x microscope or by a professional. Any flaw on the surface is called a 'Blemish' and internal flaws are known as 'Inclusions'. While very very few diamonds are perfectly clear, the closer it comes to being flawless - the higher its value because of its rarity.
The GIA Clarity scale refers to the number, location, size and type of inclusions. Generally, the fewer or smaller the clarity characteristics, the more beautiful, rare and valuable the diamond will be. 

Isle of Her 4Cs Guide Clarity Grade Scale

The scale ranges from 'Internally Flawless' (IF) to 'Included'  (I1, I2 and I3), the latter being where inclusions are easily visible to the naked eye and not generally recommended. A diamond that falls between 'Very Slightly Included' (VS1 or VS2) or 'Slightly Included' (SI1 and SI2) are usually a safe bet because you will rarely be able to naturally see any of the marks within the diamond. 
So until and unless you are a stickler for perfection, trying to attain 'perfect' clarity should not be the top priority in choosing a diamond!

Isle of Her Tips & Tricks! 

  • Remember, diamonds are formed in nature so do not strive for perfection with Clarity! 
  • Clarity characteristics don't impact the shine and sparkle of the diamond, so it's always best to up your 'Cut' lever instead. 
  • If buying a diamond online, always ask to see the Diamond Report (i.e. certification) and if available, a video too, so you can see the specifics of the stone for yourself, but don't let the red or green clarity marks scare you (these are just markings on the report, and are not actually coloured!)
  • The bigger your stone (1ct or above), the higher your clarity grading should be (VS1/VS2 or SI1 at a minimum)
  • Don't be shy - ask as many questions as you need! :) 


A diamonds Colour actually translates to the lack of colour. Did you know that diamonds actually come out the earth is many different colours? Think Blue, Brown, Pink and more!). Nonetheless, the market has traditionally always valued white diamonds (like a drop of pure crystal clear water) the most precious and most valuable.

Isle of Her 4Cs Guide Colour Grading Scale
The GIA scale places diamonds on a 23 grade point ranging from D to Z. A 'D' grade diamond is at the top of the scale thereby considered 'colourless', very rare and expensive. Going down the grid the diamonds become progressively more yellow to brown to grey, with Z deemed 'slightly yellow'.
Bear in mind that most of the time, the difference is so subtle, that only a professional will be able to differentiate between the points. For example, diamonds that are rated as G or H are very faintly coloured and still of high quality. This makes them a good choice for the budget-conscious shopper. At the lower end, the human eye can actually start to detect a tinge of yellow in Diamonds that fall between J and Z so these are only recommended if you're looking to set your jewellery in Yellow Gold. 

Isle of Her Tips & Tricks!

  • Always consider the Gold finish/setting of your jewellery when considering the Colour of your diamond. For example, a diamond with an I or J colour (Slightly tinted white) will look more yellow if set in White Gold / Platinum.
  • Similar to the other C's, the bigger your stone (0.7ct or above), the higher your colour grading should be (F, G or H at a minimum)

The Fifth C: Certification

We can't stress enough how important it is to have a Diamond Certificate (or 'Diamond Report') from a reputable independent laboratory, which sets out the credentials of your diamond. Acting as a sort of 'passport' for your stone, it not only helps with piece of mind that you're getting what you paid for but also helps to ensure resale value and that it can be insured.

Our preferred laboratory is always the Gemological Institute of America ("GIA"), which is world renowned and represent the highest standard of reliability, consistency and integrity in the industry and sets the standard and scales for each of the Four C's. However, there are many others that provide the same service that are slightly more inexpensive.

Here's an example of a Diamond Report from GIA:

Remember, it's generally industry practice to only certify diamonds that are over 0.3cts and above, but it's not unheard of to have a smaller stone certified so if it's something you'd prefer - just ask! 

Isle of Her 4Cs Sample GIA Diamond Grading Report

Got any more questions - Get in touch (Email, Live Chat, DM us on Instagram - whatever works)! :)


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