We use the GIA International Diamond Grading System which is based on the 4 Cs
Read more about the 4Cs below.
What are the 4 Cs?
The 4 Cs refer to the four diamond quality factors: – Carat weight, Clarity, Colour and Cut.
GIA, or the Gemological Institute of America, is the world’s most trusted authority in diamond and gemstone quality. Their 4 Cs diamond grading system is accepted as a universal standard for measuring diamond quality, and used by virtually all jewellery professionals around the world.
Each factor is evaluated separately, but together they establish a diamond’s overall quality.
A “carat” is the measurement of how much a diamond weighs. One carat equals 200 milligrams. One carat can be further divided into 100 points. This means we can weigh diamonds very, very precisely, to one-hundredth decimals.
For example, a diamond that weighs three quarters of a carat can be expressed as 0.75ct, or “point oh seventy-five carats”.
It’s always useful to remember that a diamond’s price is determined by all of the 4Cs, not just its carat weight.
So in other words, if the other three quality factors (clarity, colour and cut) remain the same, then a diamond’s price will increase with carat weight. But if the other quality factors vary, then two diamonds of equal carat weight can have very different prices.
For example, a 1.00 carat diamond with excellent clarity will cost substantially more than a 1.00 carat diamond with poor clarity.
Want to see what different diamond carat weights look like on your hand?
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Diamonds were formed million of years ago, deep under the earth’s crust and under extreme volcanic pressure. Because of this, they often contain unique marks and small imperfections, called “inclusions”. Diamond “clarity” refers to the absence of inclusions.
In other words, the fewer inclusions, the better the diamond’s clarity.
Every diamond is unique and all diamonds contain some inclusions. Any diamond that comes close to perfection is called flawless, but they are so rare that only a few gem experts or jewellers ever get to see one.
Within the 4 Cs evaluation system, diamonds are given a clarity grade which ranges from flawless (FL), to diamonds with obvious inclusions (I3).
Assessing diamond “colour” refers to the absence of any kind of colour tint or hue in the diamond.
In other words, the more colourless a diamond is, the better its colour grade.
The GIA’s diamond colour grading system measures the degree of colourlessness in diamonds on a scale from D (best, or colourless) to Z (worst, with a clearly visible colour tint).
Many of these colour differences are so subtle that they are only visible to diamond experts under laboratory conditions. The smaller the diamond, the more difficult it is to spot these differences.
That’s why it’s important to not get too fixated on a certain diamond grade. A good jeweller will always guide you to the best colour grade for your budget.
Most people who love diamonds say that they’re attracted to the stone’s beautiful “sparkle”. This is of course due to how diamonds reflect and “play” with light.
How well a diamond interacts with light is largely determined by its cut. Therefore, the cut affects a diamond’s beauty, as well as its value.
The quality of a diamond’s cut depends on the skilled craftsmanship and experience of the person who carved and polished it from a rough stone.
Of all the 4Cs, the cut is the most complex factor for a diamond expert to evaluate.
When measuring a diamond’s cut grade, gemmologists assess the external and internal light reflection (brightness), the way the stone scatters white light into all colours of the rainbow (fire) and the sparkle and patterns of light and dark caused by reflections within the diamond (scintillation).
Finally, a diamond’s overall appearance, as well as its durability, design, polish and symmetry, must be taken into consideration.
Note – a diamond’s “cut” does not refer to its shape (round, princess, emerald, pear), but how successfully it plays with light.
Need more advice? Don’t hesitate to contact us
Diamonds are beautiful. Take care not to fall into the trap of searching for a particular quality combination. A good diamond jeweller will be able to guide you to the best combination for your budget. As each diamond is unique, diamond clarity grades should only be used as a guide.
Our expert customer service staff are always happy help with any questions that you may have. To live chat with us, simply click on the orange tab in the bottom left corner of our website. Alternatively, email us on sales@thediamondstore.com.
We want you to feel completely confident when you shop with us. That’s why we offer FREE 30-day returns for refunds and 60-day exchanges across the UK and Northern Ireland.
If you’ve ordered a ring smaller than a size J or larger than a size Q, don’t worry — these are custom sizes, but we’re still happy to offer a free exchange or resizing if the fit isn’t quite right.
Changed your mind? No problem — you can cancel your order anytime before it’s been dispatched.
Just reach out to our friendly team via Live Chat, by email at customerservice@thediamondstore.com, or give us a call on 0345 084 1200 (or +44 345 084 1200 if calling from outside the UK). Please have your order number handy to help us assist you as quickly as possible.
Please note that for rings smaller than size J or larger than size Q, the width may vary slightly (up to 10%) due to the crafting process. If you need any adjustments, we’re happy to help.
If your item arrives damaged or defective, we’ll make it right — fast. We’ll either repair or replace it at no cost to you, or provide a refund once it’s been assessed by our head jeweller.
Our standard returns policy is 30 days to return, and 60 days to exchange.
We stand by the quality of our jewellery. That’s why all our pieces come with a 5-year warranty against defects in materials or craftsmanship. Every item is also fully hallmarked according to UK legislation, confirming its authenticity and origin.
Once we’ve received and inspected your returned jewellery, we’ll process your refund right away and email you to confirm. Depending on your bank or payment provider, it may take 3 to 5 working days to show up on your statement.
We’ll always refund you via the same method you used to make your purchase — whether that was credit or debit card, PayPal, Pay4Later Finance, bank transfer, or another option.
To avoid delays, make sure to include the returns label print-out with your parcel. This helps us identify your return quickly.
We’re proud to say that all our diamonds are conflict-free and fully compliant with United Nations regulations. When you buy from us, you’re choosing ethical beauty.
We’re here whenever you need us.
📧 Email us: customerservice@thediamondstore.com or returns@thediamondstore.co.uk
📞 Call us: 0345 084 1200 (UK) or +44 345 084 1200 (International)
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