Education
As part of your diamond jewellery buying experience, it is important to understand how a diamond is graded in terms of its characteristics. An estate agent, for example, can't determine the price of a house without knowing its size, condition, location etc. This is also true for a diamond.
Fortunately, there is an internationally recognised system for diamond grading - called the "4Cs".
These are:
Before embarking on the diamond education process, you might find it useful to visit our Glossary of Terms.
CUT
The cut of diamonds most usually refers to the actual physical shape of diamonds, with round brilliant cut diamonds being the most available and popular, comprising around 70% of the total market, with other 'fancy' shaped diamonds also available.
The cut can also refer to the way the diamond is proportioned. The better the cut of diamonds, typically the more brilliance displayed and, therefore, the greater the value. Cut grades are generally classed as one of Fair, Good, Very Good or Excellent. NOTE - Not all diamonds have a cut grade. Call us on 0845 355 1164 for more information. 
ROUND BRILLIANT CUT - The most popular of all the diamond shapes, with 58 facets which are cut to maximise the sparkle and fire of the diamond. Click here to view round brilliant cut diamond engagement rings.
Hint...look for
Depth 58-63% & Table 53-60%
Symmetry & Polish - Good+
PRINCESS CUT - Having grown in popularity in recent years, princess cut diamonds are square in shape a dn have 76 facets, so display wonderful sparkle and brilliance. Click here to view princess cut diamond engagement rings.
Hint...look for
Depth 60-75% & Table 60-75%
Symmetry & Polish - Good+
Length to Width Ratio - As close as possible to 1.00:1.00
EMERALD CUT - Rectangular in shape, emerald cut diamonds are 'step-cut' and have rows of facets, usually 48 to 50, that resemble a staircase.Click here to view emerald cut diamond engagement rings.
Hint...look for
Depth 60-69% & Table 60-75%
Symmetry & Polish - Good+
Length to Width Ratio - Close to 1.50:1.00
MARQUISE CUT - These diamonds are long and slender and have 56 facets, so wonderful sparkle. Click here to view marquise cut diamond engagement rings.
Hint...look for
Depth 59-65% & Table 52-64%
Symmetry & Polish - Good+
Length to Width Ratio - Between 1.75:1.00 - 2.10:1.00
OVAL CUT - These provide a similar amount of sparkle to round cut diamonds and have 56 facets. Click here to view oval cut diamond engagement rings.
Hint...look for
Depth 58-65% & Table 54-64%
Symmetry & Polish - Good+
Length to Width Ratio - Between 1.33:1.00 - 1.66:1.00
PEAR CUT - Traditionally a teardrop in shape, pear cut diamonds have a total of 58 facets, prokecting superb sparkle. Click here to view pear cut diamond engagement rings.
Hint...look for
Depth 58-65% & Table 52-64%
Symmetry & Polish - Good+
Length to Width Ratio - Between 1.40:1.00 - 1.75:1.00
HEART CUT - These are essentially pear cut diamonds with a cleft at the top. Click here to view heart cut diamond engagement rings.
Hint...look for
Depth - 58-65%
Table - 55-60%
Symmetry & Polish - Good+
Length to Width Ratio - Close to 1.00:1.00
RADIANT CUT - These diamonds are either rectangular or square in shape with cut corners, with around 70 facets.
Hint...look for
Depth 60-69%
Table 60-69%
Symmetry & Polish - Good+
Length to Width Ratio - Close to 1.00:1.00 for squarish, or 1.10+:1.00 for elongated
ASSCHER CUT - Asscher cut diamonds are typically square in shape with chamfered corners, with the 57 step cut facets of emerald cut diamonds.
Hint...look for
Depth - 60-70%
Table - 60-70%
Symmetry & Polish - Good+
Length to Width Ratio - Between 1.00:1.00 - 1.05:1.00
CUSHION CUT - Cut with a total of 60 facets, cushion cut diamonds are similar to round diamonds or oval cut diamonds.
Hint...look for
Depth - 65-75%
Table - 65-75%
Symmetry & Polish - Good+
Length to Width Ratio - Close to 1.00:1.00, or 1.10+:1.00 for elongated
There is also a cut of diamonds which is called Hearts & Arrows. This cut of diamond is for round brilliant cut diamonds and signfies the perfect cut of diamond, for which you will often pay a premium. At DeJoria Diamonds, we are able to source hearts & arrows cut diamonds - please call us on 0845 355 1164 for more information. For more general information on hearts & arrows cut diamonds, click here.
CARAT SIZE
The word "carat" is taken from the carob seeds that people once used in ancient times to balance scales. This was standardised in 1907 - one carat became 0.2 grams. Furthermore, once carat is divided into 100 "points". Therefore, 25 points is ¼ carat, 50 points is ½ carat and so on.
Diamonds are rare. The larger the diamond, the rarer it is - larger diamonds, therefore, have a greater value per carat. For that reason, the price of a diamond rises exponentially with its size. This is not always to say, however, that the larger the diamond the more valuable it is compared with a smaller stone. This is dependent upon other characteristics as well.
The following table shows key carat weights relate to size in millimetres for various shaped diamonds.
|
Approximate stone sizes in millimetres | |||||||
| Carat Weight |
Round Brilliant |
Princess | Emerald | Marquise | Oval | Pear | Heart |
| 0.25ct | 4.2 | 3.3sq | L4 x W3 | L5 x W3 | L5 x W3 | L4.5 x W2.5 | 3.9 |
| 0.30ct | 4.4 | 3.5sq | L4.5 x W3 | L6 x W3 | L5 x W3.25 | L5 x W3 | 4.0 |
| 0.33ct | 4.5 | 3.7sq | L5 x W3 | L6.5 x W3.5 | L5 x W2.75 | L5.25 x W3.25 | 4.5 |
| 0.40ct | 4.8 | 3.9sq | L5 x W4 | L7 x W4 | L5 x W4 | L5.5 x W3.5 | 4.75 |
| 0.45ct | 5.0 | 4.0sq | L5.5 x W4 | L7.5 x W4 | L5.25 x W4.25 | L5.75 x W3.75 | 4.8 |
| 0.50ct | 5.2 | 4.2sq | L6 x W3 | L8 x W4 | L5.5 x W4.5 | L6 x W4 | 4.8 |
| 0.55ct | 5.4 | 4.4sq | L6 x W3.5 | L8 x W4.5 | L5.75 x W4.5 | L6.25 x W4.25 | 4.95 |
| 0.60ct | 5.5 | 4.5sq | L6 x W4 | L8.25 x W5.5 | L6.25 x W4.5 | L6.4 x W4.4 | 5.1 |
| 0.65ct | 5.7 | 4.6sq | L6.25 x W4 | L8.5 x W6.5 | L6.5 x W4.5 | L6.6 x W6.6 | 5.25 |
| 0.70ct | 5.8 | 4.75sq | L6.25 x W4.25 | L9 x W4 | L6.75 x W4.75 | L6.8 x W6.8 | 5.4 |
| 0.75ct | 5.9 | 4.8sq | L6.5 x W4.5 | L9 x W4.5 | L7 x W5 | L7 x W5 | 5.6 |
| 0.80ct | 6.1 | 4.85sq | L6.75 x W4.5 | L9 x W5 | L7.1 x W5.1 | L7.2 x W5 | 5.8 |
| 0.85ct | 6.2 | 4.9sq | L6.75 x W4.75 | L9.25 x W5 | L7.2 x W5.2 | L7.4 x W5 | 5.9 |
| 0.90ct | 6.3 | 5.0sq | L6.85 x W4.85 | L9.5 x W5 | L7.3 x W5.3 | L7.6 x W5 | 5.95 |
| 0.95ct | 6.4 | 5.1sq | L7 x W4.85 | L9.75 x W5 | L7.4 x W5.4 | L7.8 x W5 | 6.0 |
| 1.00ct | 6.5 | 5.25sq | L7 x W5 | L10 x W5 | L7.5 x W5.5 | L8 x W5 | 6.0 |
| 1.25ct | 7.0 | 5.9sq | L7.5 x W5.5 | L10.5 x W5 | L8 x W6 | L8.5 x W5.5 | 6.5 |
| 1.50ct | 7.5 | 6.0sq | L8 x W6 | L11 x W5 | L8.5 x W6.5 | L9 x W6 | 6.9 |
| 1.75ct | 7.9 | 6.25sq | L8.25 x W6.25 | L11 x W5.5 | L9 x W6 | L9.5 x W6.5 | 7.3 |
| 2.00ct | 8.2 | 6.5sq | L8.5 x W6.5 | L12 x W6 | L9 x W7 | L10 x W7 | 7.5 |
| 2.25ct | 8.5 | 7.0sq | L8.75 x W6.75 | L12.5 x W6 | L9.25 x W7.25 | L11 x W7 | 7.9 |
| 2.50ct | 8.9 | 7.5sq | L9 x W7 | L13 x W5.5 | L9.5 x W7.5 | L12 x W7 | 8.4 |
| 2.75ct | 9.0 | 8.0sq | L9.5 x W7.5 | L13 x W6 | L9.75 x W7.75 | L12.25 x W7.5 | 8.6 |
| 3.00ct | 9.4 | 8.25sq | L10 x W8 | L14 x W7 | L10 x W8 | L12.5 x W7.75 | 8.9 |
| 3.25ct | 9.6 | 8.5sq | L10.25 x W8.25 | L14.5 x W7 | L10 x W8.25 | L12.75 x W8 | 9.1 |
| 3.50ct | 9.9 | 8.75sq | L10.5 x W8.5 | L15 x W7 | L10 x W8.5 | L13 x W8.25 | 9.4 |
| 3.75ct | 10.1 | 9.0sq | L10.75 x W8.75 | L15.5 x W8 | L10.5 x W8.75 | L13.25 x W8.75 | 9.6 |
| 4.00ct | 10.4 | 9.25sq | L11 x W9 | L15.5 x W8.5 | L11 x W9 | L13.25 x W9 | 9.9 |
You can download this PDF document and print it out to see diamond sizes to scale, at the various carat weights -
DOWNLOAD DIAMOND SIZES PDF [Opens in a new window]
COLOUR
The most valuable diamonds are colourless. They allow most light to pass through the stone and create the most brilliance. However, very few diamonds are colourless, so most diamonds will have some yellow in them - the less yellow the better. The colour scale goes from D to Z (no diamond of colour A, B or C has ever been found), with D being the most white and Z being the most yellow. At DeJoria, our minimum quality threshold is colour J (slightly tinted yellow). For comparison purposes, the majority of diamonds in a high street jewellers shop are 'Commercial grade' quality which, if graded on this scale, would be approx colour K / L.
D - Exceptionally white
E - Exceptionally white
F - Rare White
G - White
H - White
I - Slightly tinted white
J - Slightly tinted white
Any diamonds with a colour grade of less than J are rejected.
CLARITY
The clearer the diamond, the greater its brilliance, and the greater its value. Most diamonds have blemishes, called 'inclusions' which are nature's birthmark of the stone. These can be tiny traces of carbon (black spots), air pockets (white spots) or other naturally occurring phenomena. Diamond clarity ranges from diamonds without any flaws (internally flawless) to those that have visible inclusions. At DeJoria, our minimum quality threshold is SI2 ("Slightly Included" - not visible with the naked eye). For comparison purposes, the majority of diamonds in a high street jewellers are 'Commercial grade' quality which, if graded on this scale, would be approx clarity I1 / I2.
IF - Flawless, or Internally Flawless
VVS1 - Very, Very Slightly Included. Requires 60x magnification to see any inclusions
VVS2 - Very, Very Slightly Included. Requires 60x magnification to see any inclusions
VS1 - Very Slightly Included. Requires 30x magnification to see any inclusions
VS2 - Very Slightly Included. Requires 30x magnification to see any inclusions
SI1 - Slightly Included. Generally requires 10x magnification to see any inclusions.
SI2 - Slightly Included. Generally requires 10x magnification to see any inclusions
Any diamonds with a clarity grade of less than SI2 are rejected.
CERTIFICATION
Whilst the acquisition of a diamond engagement ring or other piece of diamond jewellery is an important expression of love or accomplishment, it also represents a major investment in time, energy and money. You need and deserve to feel confident in the integrity of what you've acquired. There is no typical industry standard for diamond certification in the UK - and therefore, you'll find that the majority of diamond jewellery in a high street jewellers will be non-certified. At DeJoria, we believe it is vital that you buy certified diamonds for your peace of mind. At DeJoria, we use GIA, IGI, AGS, HRD and EGL certified diamonds. Click here for more information.
CONFLICT-FREE 
Today, an illegal trade exists within the diamond industry whereby the profits generated by the mining of diamonds - predominantly in 3rd world countries - have been used to fund wars and terrorist activity. These are known as "conflict diamonds" or "blood diamonds". The Kimberley Process was established in 2000 between governments across the world in an attempt to eradicate this disgraceful activity, and DeJoria wholeheartedly supports this initiative for we believe that wherever you purchase your diamond engagement rings, diamond eternity rings, diamond rings and diamond jewellery, the diamonds should ALWAYS be conflict-free, and not tarnished by a dark history. For more information, click here.
CONFIDENCE 
INDEPENDENT INSURANCE VALUATIONS
DeJoria also provides an independent insurance valuation dossier on all 'Create Your Diamond Ring' items and higher valued
items in our 'Diamond Gift Boutique', where the item is appraised and examined by an independent gemologist. This dossier serves 2 important purposes - Firstly, it provides our clients with complete piece of mind that the diamond jewellery they have purchased is indeed the genuine article. Secondly, loss or damage of a personal item is always distressing, but think how much worse it would be if you have no idea of the worth of the item you have lost and have no way of convincing your insurer of its value. SafeGuard take digital photographs of the diamond jewellery, note any distinguishing features, take a full and accurate description and place a value upon the item for insurance purposes. All this information is permanently stored onto a national computer database providing our clients, the police and your insurer with conclusive proof of ownership.
SafeGuard Quality Assurance Insurance Limited is located within the UK Assay Office - the UK's leading gemmological authority. It was founded by Act of Parliament in 1773 and its prime function is to carry out independent testing and hallmarking.
Click here to visit the website for SafeGuard Quality Assurance Limited.
Single purchases in excess of £10,000 will be accompanied by a 'Jewellery Portfolio' as part of our package. This provides a comprehensive description and valuation of the diamond jewellery, high quality images of the item, and helpful information to explain diamond grading, hallmarking and jewellery care. All this is provided in a luxury leather presentation wallet.
HALLMARKING
It is consumer law in the UK that all precious metal jewellery carry a hallmark. This is a tiny stamp on the inside of the ring mount which is your assurance that the platinum or gold in your precious metal jewellery is indeed that. Hallmarking in this country is carried out by one of the UK Assay Offices - London, Birmingham, Sheffield or Edinburgh. We only use the best quality 950 platinum, or 18kt white / yellow gold for our jewellery. Visit our precious metals page for more information.
BRITISH JEWELLERS' ASSOCIATION
The British Jewellers Association is the national trade association which promotes and protects the growth and prosperity of UK jewellery companies. We adhere and support the BJA's Code of Ethics, which are outlined on the our credentials page.
