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About Diamonds


Diamonds are said to be graded according to a set of factors known as the 4 C's. However, this is not really the full story as the 4 C's are a marketing term created due to the perceived need to provide quick and simple explanations to the diamond buying public. This has led to a confusion among the public which we hope to put right in as direct a way as possible. 


The most problematic of the 4 C's is the term "Cut" which, when applied to gemstones has come to encompass a variety of different meanings. These include the actual shape of a diamond, its proportions, its reflective and refractive qualities and the dimensions which affect its symmetry. Diamonds are "cleaved" and then "polished" they are not cut. The cut of a diamond is an industry term used to describe the shape of a diamond, not its finished qualities. "Make" is the term we use to describe the quality of the polishing and includes factors such as the proportions, the symmetry and the precision of the faceting. The proportions of a diamond determine the amount of liveliness or fiery sparkle within it.

When a rough diamond is polished, the polisher attempts to reveal its three hidden qualities. These are reflection, refraction and scintillation (life and fire). As reflection and refraction are mutually opposites the polisher must compromise these two qualities and attempt to maximise scintillation. A diamond that is badly made will not reflect light properly and its fire will be greatly reduced.

In our considered opinion, the quality of polish, is the most important factor in determining a truly beautiful diamond. A diamond that is described as having a "deep cut" will result in an irregular sparkle, whereas a diamond said to have a "shallow cut" will appear lifeless as the light will pass through it, rather than being reflected back through the top of the stone. A polished diamond with proportions conforming to an internationally accepted range of measurements, described as "good to ideal cut", will radiate with sparkle.

Rough diamonds have been and continue to be polished into literally dozens of shapes. Some shapes, such as heart shaped (or to use its technicaly correct name "Heart-Shaped Modified Brilliant") are only slight variations from the most recognisable, the round brilliant cut while others (like marquise diamonds) are more extreme departures. We use the traditional brilliant cut (round) diamonds and of course, heart shape diamonds in the manufacture of items within our exclusive range of fine jewellery. Each stone is calibrated in order to show its full brilliance and to perfectly complement our beautiful and timeless designs.



The colour of a diamond significantly affects its price, the less colour a diamond shows, the better. Although some diamonds are colourless making them rare and highly valuable, almost all show colour ranging through various shades of yellow or brown. The scale used to grade diamond colour starts at D for colourless diamonds and runs through the alphabet to Z for diamonds that show a strong colour, are more common and therefore less expensive. Although only diamonds with a colour of D to F are technically considered colourless (and thus command premium prices), for all practical purposes, diamonds up to colour I will tend to appear colourless to all but a trained gemologist working under ideal lighting conditions. The more common and therefore less expensive diamonds graded from K upwards will show visible colour and from N upwards the colour is increasingly perceptible. Taking this information into consideration we advise that diamonds of G - I colour offer the best value, as we believe there is little reason to pay a premium for an undetectable colour difference and as such we do not use any diamonds that have a lower colour than I.

Please note that the above scale is only used to grade standard diamonds not to be confused with "fancy diamonds", extremely rare and valuable gems that have intense colours such as pink or yellow. At present we do not use any fancy diamonds within our range.



All diamonds contain impurities known as inclusions. These are made up of small bits of carbon and other minerals present when the diamond was formed. The clarity of a diamond is determined by the size, amount, colour and position within the diamond of these inclusions.

A diamond that has no visible impurities when looked at through a 10x magnifying glass (or loupe) is classed as IF (internally flawless). This is the the highest grade of clarity for diamonds used in the jewellery industry, however you must expect to pay a very large premium for IF diamonds. The next grade down is VVS (very very slightly included) which is subdivided into VVS 1 or VVS 2. VVS diamonds have tiny inclusions which are difficult to detect, even under magnification. VVS diamonds also carry a large price premium.

The term VS (which is also subdivided into VS 1 & VS 2) indicates a diamond which has very slight imperfections. To all except those with a trained eye, VS diamonds appear to be free of inclusions. In our opinion this grade of diamond (in conjunction with the other 3 C's) offers optimal value, which is why VS is the lowest grade we use for the smaller brilliant cut diamonds set in our diamond collection Claddagh rings. SI (again subdivided between SI 1 & SI 2) is the term used to describe diamonds which, when viewed under 10x magnification are seen to contain small inclusions. As there is an imperceptible difference in the appearance of these diamonds, only the sharpest eyed can spot these inclusions. We find this an ideal grade for the heart shaped diamonds that we use in our range of jewellery as they represent fantastic value for money.

The lowest grades of diamonds used in jewellery are I1, I2 and I3 (or included but also known as Pique). Diamonds from these grades will have varying degrees of black spots clearly visible to the naked eye. We do not use any diamonds from these grades and we advise our customers away from them as the impurities they contain detract in no small way from their beauty and sparkle.



Carat, the standard unit used in measuring the weight of diamonds and other gemstones, is the final factor influencing the desirability and value of a diamond. One carat (weighing 0.2 grams) is subdivided into "points", where 100 points is one carat. In pieces of jewellery with more than one stone, such as those in our diamond collection Claddagh Rings, the total carat weight is the combined weights of all the stones in the item. So a total carat weight of 75 points can also be expressed as 0.75 carat or 3/4 of a carat.

Basically speaking, taking into consideration all the above factors, the bigger and heavier a diamond is the higher its value will be. However it is important to remember that a poorly cut large diamond of low colour or one that is heavily included will be less valuable and much less attractive than a well cut, clean and white diamond of a smaller size.


The above chart is a rough guide for round brilliant diamonds. Meaurements will vary for different cuts. The above images are not to scale.

Here at Lazlo Jewellers we can make a diamond engagement ring to suit every style and budget email us on or call us at 091564544 to discuss your specific requirements.