The Diamond 4C's

Cut, Colour, Clarity & Carat


Gemologists agree that the cut of a diamond is the key to its brilliance. When comparing 2 diamonds with the same colour, a diamond that is cut with the right proportions will be much more brilliant than a poorly cut diamond. Therefore, if a diamond has a beautiful colour and good clarity, but is incorrectly cut , it will lose a lot in appearance. By cut, we mean the finish, the dimensions, the return of the light to the eye as well as the polishing and the symmetry. It goes without saying that these notions of cut represent an essential factor in the beauty and quality of a diamond, which only an experienced craftsman can master.


Diamonds are also classified by colour. Since the most sought-after colour is colourless, or the absence of colour, the less coloured the diamond , the higher its value. According to the diamond coloured classification scale published by the GIA (Gemological Institute of America), diamonds are classified from colourless to coloured (from white to yellow to brown) using the different letters of the alphabet. The colour-grading begins with the letter D, which represents the colourless and continues to the letter Z, according to the growing presence of colour. Thus, the perfect note for a diamond is not an A, but a D! Part of a separate class, "fancy" coloured diamonds can have very high value given their rarity and colour intensity.


Because they form deep in the earth, most diamonds contain internal foreign bodies, called inclusions, and external defects. In the vast majority of cases, the inclusions are caused by small black carbon crystals that can become trapped during the formation of the diamond. Diamonds with very few foreign bodies are rarer and, of course, will see their value increased. Using the International Diamond ™ classification system, created by GIA, we classify diamonds by category of clarity. In the determination of purity, we must consider the position, quantity, size, colour and nature of the impurities visible under enlargement 10 times.


The weight of a diamond is one of the determining elements of its price. The measurement unit used to determine the weight of a diamond is the carat. A carat is divided into 100 points; thus, a 25-point diamond is equivalent to a quarter of a carat, and a 50-point is equivalent to half a carat. Large stones being rare, the price of a diamond evolves exponentially depending on its weight.

Natural Diamonds

Natural diamonds are diamonds that were created in nature millions of years ago. Created under intense heat and high pressure, natural diamonds are as unique as they are rare. This is precisely what gives them their value. Coming mainly from Canada, St-Onge natural diamonds are still the most prized today.

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Lab Grown Diamonds

Lab grown diamonds (or Lab created diamonds or man-made diamonds) have the same chemical, physical and optical characteristics as natural diamonds. They are created in a laboratory using state-of-the-art technologies reproducing the same conditions under which natural diamonds formed. Lab grown diamonds is an alternative to natural diamonds.

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Les diamants de laboratoire ou synthétiques