facebook pixel
Search Menu

Selecting Your Perfect Diamond – Understanding The 4 C’s

20 April 20

If you starting your journey looking for a diamond engagement ring, or perhaps a piece of diamond jewellery, throughout this article we explore the main characteristics which make up the value and beauty of a diamond.

If you are looking to choose your perfect diamond an in-depth knowledge of diamonds is not necessary as our dedicated teams are here to guide you. However, a basic understanding of the key principals will certainly help you decipher the mystical quality and value of this precious stone. The 4 C’s are the basics of diamond grading, referring to the carat weight, colour, clarity and cut grade.  In diamonds, rarity equals value and these are the four main characteristics which will have an influence on the value, and beauty, of your diamond.

Your Diamond’s Carat Weight

The carat weight refers to the literal weight of the stone, although a diamond of a certain weight, cut to “ideal” proportions will typically fit into an approximate millimetre size, the most accurate way to assess this feature is by a precise weight measurement. For example, 1 carat equals 0.2 grams or a 0.75g diamond would be a 3.80ct diamond. This measurement is said to originate back when diamond traders used to weigh their small goods against carob seeds, which on average weight approximately 0.2g each, hence it’s given name – carat.

Your Diamond’s Colour

In most cases, the colour grading favourably refers to the absence of colour, particularly in diamonds. Meaning the less colour visible in the stone, the more valuable it is, except in cases of fancy colour diamonds, which are available in colours such as pink or blue. This “colour” is most commonly yellow or brown hues; however, it is very difficult for the untrained eye to notice this colour without the comparison of a diamond with a higher colour grade, a whiter diamond. The official scale ranges from D (colourless) to Z (light colour) with most diamonds used throughout jewellery being between D-M, colourless to faint colour on the scale. Here at Prestons we pride ourselves on only showcasing the highest quality diamonds throughout our jewellery collections, typically ranging from D-G. This ensures a white, and beautiful colour, for your most cherished pieces. 

Your Diamond’s Clarity

When grading the clarity of a diamond, an expert gemologist will measure the size, placement and number of internal inclusions, as well as external blemishes on a polished gemstone. These inclusions or blemishes are often referred to as characteristics as they make each diamond unique, like each of us. The scale runs from “flawless”, with practically no internal or external imperfections all the way to “Included” where there is a large number of imperfections often visible to the naked eye. A flawless diamond is incredibly rare and therefore exceptionally valuable. The clarity grading is also relative to the size, or carat, of the diamond and how these characteristics affect the overall appearance or beauty of the stone. Each diamond at Prestons is accompanied by a diamond certificate. This certificate will not only show you the grading, e.g. SI1, of a diamond but a description of the types of inclusions, or characteristics, in your diamond and for diamonds weighing 1.00ct, or over, a detailed drawing of the placement of the imperfections. 

Your Diamond’s Cut

The cut of a diamond is often thought to refer to the shape of the stone, it actually refers to the proportion and arrangements of the diamonds facets as well as the quality of the workmanship. Each of our showrooms believe that this is the most important of the 4 C’s as it has the biggest impact in the overall appearance of the diamond, offering the stone the maximum fire, brilliance and scintillation, more commonly known as sparkle, possible.  A diamond which has been expertly cut optimises and utilises the true beauty of the stone. 

If you would like to learn more about the cut, or shape, of a diamond our article Making The Cut explore this in further detail.

Our Showrooms

Over the years, generations of families have become customers of Prestons, and many have gone on to become friends. Today, our teams look forward to welcoming you to our showrooms in Wilmslow, Guildford, Norwich and Leeds.

Prestons Guildford


Our Guildford showroom, which is now located on the opposite side of the high street, is designed to reflect the architectural merit of the Edwardian building it now occupies. The store features newly extended spaces dedicated to the fine watch houses it showcases, alongside a comfortable lounge to allow our clients to explore our bridal and fine jewellery collections. Explore This Showroom

Prestons Wilmslow


Located in the heart of Wilmslow, this showroom features a selection of spaces dedicated to the fine watch houses it showcases. Of course, the bridal collections Prestons have always been famous for remain a prominent feature of the store and surround the famous Aquarium Bar which sits at its centre. Explore This Showroom

Rolex by Prestons, Leeds


This showroom, located in Victoria Gate, features extensive Rolex showcases alongside a discrete VIP lounge. Every element of the interior design radiates the values of the Rolex crown: excellence, precision and attention to detail from louvre walls in walnut, to the careful calibration of colours and patterns within the fittings and furnishings. Explore This Showroom

Prestons Norwich


Located on the historic Norwich high street, Prestons Norwich has been expanded and redesigned to reflect the character of the building it has occupied for over 150 years. The showroom features collections by Patek Philippe, Rolex and TUDOR alongside our fine jewellery collections. Explore This Showroom
Guildford showroom