The Four C’s and More: Understanding Jeweller Lingo When Diamond Shopping

The Four C’s and More: Understanding Jeweller Lingo When Diamond Shopping

Discerning a high-value diamond requires a keen eye and knowledge. Jewellers and people who deal with diamonds regularly know how to value a diamond. Aside from a diamond's value and overall look, other important considerations exist. These include the four c's and other diamond characteristics only considered by diligent and specific jewellers. 




The carat system is a standardised unit of measurement used for weighing diamonds and other gemstones. It provides a consistent way to quantify a stone's weight, which is a significant factor in determining its value.

The carat-weight of a diamond is equivalent to one-fifth of a gram, which means 1 carat is equal to 0.2 grams; this is approximately the weight of a paperclip. 

However, it's crucial to note that two diamonds with the same weight can have significantly different values based on the other components of the Four C's: clarity, colour, and cut. These factors play a pivotal role in determining a diamond's overall worth.

Large-sized diamonds are so rare that the value of diamonds does not increase in proportion to their weight. This means that a two-carat diamond will cost more than double that of a one-carat diamond.


Relationship between Carat Weight and Size: 


While carat weight is often associated with a diamond's size, it's not the sole determinant. Different diamonds can have the same carat weight but vary in dimensions due to variations in their cut, shape, and proportions. How a diamond is cut can significantly impact its visual size and overall appearance.




Spread refers to how a diamond's weight is distributed across its physical size. Diamonds with ideal cut proportions can appear larger (have a greater spread) for their carat weight, as they reflect more light and maximise their visual appeal. On the other hand, diamonds with poorer cut quality may have a smaller spread, appearing smaller for their carat weight.


Face-up Appearance: 


The face-up appearance of a diamond refers to how it looks when viewed from the top. Two diamonds with the same carat weight but different dimensions can have noticeable differences in their face-up appearance. Factors such as table size, crown height, and pavilion depth can affect how the diamond appears to the naked eye.


When selecting a diamond, it's crucial to consider the interplay between carat weight, dimensions, and the other components of the Four C's (clarity, colour, and cut). Finding the right balance among these factors is essential to achieve a diamond that meets your desired size, appearance, and overall quality.


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When diamonds are created naturally, they can have a variety of characteristics called inclusions and blemishes. The clarity of a diamond (Four C's: Carat, Colour, Cut and Clarity) refers to the absence of these characteristics.


The number of inclusions or blemishes in your diamond will determine how flawless it is. Diamonds that are free from these blemishes are considered rare, and their rarity directly impacts their value.


The GIA International Diamond Grading System™ is utilised to assign diamonds a clarity grade, ranging from flawless (FL) to diamonds with obvious inclusions (I3). This will affect the transparency and brilliance of the diamond depending on where it sits on the scale. However, unless the clarity sits towards the bottom of the scale (slightly included or included), in most cases, it would be very hard to notice many of the inclusions or blemishes without a magnifier or microscope. 


The GIA Clarity Scale comprises 11 grades, with most diamonds falling into the VS (very slightly included) or SI (slightly included) categories. When determining a clarity grade, the GIA system considers various factors, including the size, nature, position, colour or relief, and quantity of clarity characteristics visible under 10× magnification. This meticulous assessment ensures a comprehensive evaluation of a diamond's clarity characteristics.


The GIA Clarity Scale provides a comprehensive grading system for diamonds:

  • Flawless (FL): No inclusions or blemishes are visible to a skilled grader using 10× magnification.
  • Internally Flawless (IF): There are no inclusions; only minor polishing marks are visible under 10× magnification.
  • Very, Very Slightly Included (VVS1 and VVS2): Inclusions are challenging for a skilled grader to detect under 10× magnification.
  • Very Slightly Included (VS1 and VS2): Inclusions are minor and can range from difficult to somewhat easy for a skilled grader to observe under 10× magnification.
  • Slightly Included (SI1 and SI2): Inclusions are noticeable to a skilled grader under 10× magnification.
  • Included (I1, I2, and I3): Inclusions are visible under 10× magnification and may impact the diamond's transparency and brilliance.



Image credit: Diamond Buzz





Cut refers to how well a diamond's facets interact with light. The cut depends on the proportions, symmetry, and polish to ensure the most light return possible in the diamond. 


Cut encompasses two important aspects in the diamond and jewellery industry:


Firstly, it refers to the unique shape and style of a polished diamond, such as the Marquise and Oval cut, two elongated cuts currently a popular diamond cut choice. Secondly, within the context of the "4Cs (Carat, Colour, Clarity, Cut),"  cut signifies the relative quality of a polished diamond's proportions and finish. This includes factors like the diamond's symmetry, polish, and the precision with which its facets are crafted.


It's worth noting that cut grades are exclusively assigned to round diamonds in diamond grading reports, while other diamond shapes do not have specific cut grades.


Out of the 4Cs, the cut holds immense significance as it directly influences a diamond's visual appeal. The diamond cutter plays a vital role in determining how to bring out the maximum beauty from a rough diamond.


Considered optical marvels, polished diamonds ideally reflect and refract light in captivating ways, creating a brilliant display for the viewer. Refer to the illustrations below to visualise this captivating phenomenon.


The skilled cutter carefully studies the rough diamond to strategise the best approach for enhancing its beauty during the diamond-cutting process. In addition to maximising beauty, a commercial aspect is involved, where the cutter aims to retain as much weight as possible to increase the diamond's perceived value. However, prioritising weight retention can sometimes lead to a compromised face-up appearance, resulting in either a bulky, small-diameter diamond or a spread-out, wide-diameter one. It's essential to consider minimum diameter recommendations, especially when purchasing round brilliant diamonds. 


Diamonds with cut grades of "Fair" or "Poor" may exhibit certain issues, such as excessively deep pavilions causing light leakage or overly shallow/spread pavilions resulting in a "fish eye" effect. For this reason, we do not work with diamonds with "Fair" or "Poor" cut grades. 


GIA (Gemological Institute of America) utilises seven essential components to evaluate the cut of a round brilliant diamond. These components include brightness, fire, scintillation, weight ratio, durability, polish, and symmetry. By considering these factors, GIA determines the diamond's cut grade, which ranges from Excellent to Poor. The final grade is determined based on the lowest assessment received for five out of the seven components. In simpler terms, if a diamond receives a Poor grade for brightness, its overall cut grade cannot exceed Poor. However, polish and symmetry follow a different assessment method, aligning with GIA's standard grading methodology. For instance, a diamond with Very Good polish and/or symmetry may still achieve an Excellent cut grade.


When you receive a GIA Diamond Grading Report, it provides a comprehensive evaluation of the diamond's cut, along with a diagram illustrating its proportions and relative measurements. Consider this report an invaluable tool to assist you in selecting a stunning diamond. 



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The value of white diamonds is closely tied to their ability to exhibit colourlessness. While diamonds are primarily composed of carbon, they also contain minute amounts of other elements that contribute to the presence of colour tints, such as yellow, grey, and brown. The less colour present in a diamond, the higher its value.


However, it's important to note that there are exceptions to this rule, specifically with Fancy Colour diamonds that fall outside the traditional colour range. Fancy colour diamonds, such as vibrant pinks and blues, are uniquely appealing due to their extreme rarity and high value. 


The colour-grading scale developed by GIA (Gemological Institute of America) is widely recognised as the industry standard for diamonds. This scale starts with the letter D, representing the highest grade of colourlessness. It progresses through the alphabet to the letter Z, which signifies light yellow or brown hues. Each letter grade within the scale corresponds to a specific range of colour appearance.


To determine the colour grade of a diamond (Four C's: clarity, carat, cut and colour), it is carefully compared to a set of standard "master" diamonds of known colour under controlled lighting conditions and precise viewing parameters. This meticulous evaluation ensures accurate and consistent colour grading, allowing for reliable diamond comparisons.


GIA's colour-grading scale provides a standardised framework for assessing and communicating the colour characteristics of diamonds in the industry. 


While some colour distinctions in diamonds may be imperceptible to the untrained eye, these subtle variations significantly impact the quality and price of the diamond.


Even though the differences may appear minor, the slightest colour variation can greatly affect a diamond's overall quality and value.


The ability to discern these subtle colour differences requires expertise and trained observation. These distinctions are crucial when it comes to Layla Kaisi Collection assessing the best option for your preferences and budget.  


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Proportions + Ratio


Proportions and ratios refer to the dimensions and relationships between different parts of a diamond, such as the table size, crown angle, pavilion depth, and girdle thickness. These proportions significantly influence the diamond's ability to reflect light and, thus, its overall sparkle and brilliance. Optimal proportions ensure that light entering the diamond is properly refracted and reflected back to the observer's eye, maximising the diamond's fire and brilliance. Light can escape from the sides or bottom when proportions are not ideal, diminishing the diamond's visual appeal.


Layla Kaisi Collection meticulously selects diamonds with optimal proportions, ensuring each stone maximises its visual impact. Every diamond chosen exhibits exceptional brilliance from all angles, with a face-up appearance that appears larger than its carat weight suggests. The carefully curated selection process guarantees minimal shadowing and optimal light performance, resulting in diamonds that truly sparkle and shine.






Faceting Map


A faceting map is a diagram that shows the arrangement and shape of a diamond's facets (the flat, polished surfaces on a diamond). This map is essential for understanding how a diamond interacts with light. Different facet arrangements can enhance or diminish the diamond's brilliance and fire. A well-designed faceting map ensures the facets are cut to maximise light return, contributing to the diamond's overall beauty.


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Diamond Depth %


Diamond depth percentage is the ratio of the diamond's depth (measured from the table to the culet) to its diameter, expressed as a percentage. The ideal depth percentage varies depending on the diamond shape but typically ranges from 59% to 62% for round brilliant cuts. Proper depth ensures optimal light performance; too shallow or too deep cuts can result in light leakage, reducing brilliance and fire. Layla Kaisi Collection adheres to stringent standards in diamond selection, focusing on optimal depth percentages for each diamond shape. This meticulous approach ensures that every stone, regardless of its cut, meets the ideal depth range for its specific shape. This careful selection process results in a curated assortment of diamonds that consistently display the best possible proportions and scintillation, offering clients exceptional quality and visual appeal in every piece. 



Girdle Thickness and Type (Faceted or Smooth)


The girdle is the outer edge of the diamond where the crown (top part) meets the pavilion (bottom part). Girdle thickness can vary from very thin to extremely thick; its type can be faceted or smooth. A faceted girdle has small polished faces, while a smooth girdle is polished but not faceted. Ideal girdle thickness is important to prevent chipping and balance the diamond's overall look. A very thin girdle is prone to damage, while an extremely thick girdle can add unnecessary weight without enhancing appearance.


Poor Cut

Excellent Cut



Crown Height


Crown height is the distance from the girdle to the top of the diamond, measured as a percentage of the diamond's overall diameter. This height affects the diamond's light dispersion and fire. An ideal crown height allows optimal light entry and refraction, enhancing the diamond's sparkle. Too high or too low a crown can negatively impact the diamond's aesthetic and light performance.



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Fluorescence refers to the diamond's ability to emit visible light when exposed to ultraviolet (UV) rays. It can range from none to very strong. In some cases, strong fluorescence can cause a diamond to appear hazy or milky, affecting its visual appeal. However, for most diamonds, fluorescence has a minimal impact on appearance. A faint to medium fluorescence can make a lower colour grade diamond appear whiter and more vibrant in certain lighting conditions.





Inclusion Distribution


Inclusion distribution describes how internal flaws (inclusions) are spread throughout the diamond. Evenly distributed, minor inclusions are less noticeable and can be hidden by the diamond's facets. However, large, concentrated inclusions can significantly impact the diamond's clarity and brilliance. Layla Kaisi Collection pays close attention to the size, type, and placement of inclusions, avoiding all diamonds that have inclusions in visible locations such as the table or crown. Understanding inclusion distribution helps evaluate the diamond's overall clarity and visual appeal.


Types of Inclusions:

- Pinpoint: Tiny, dot-like inclusions, often white or colourless.

- Feather: Hairline fractures within the diamond can appear white or transparent.

- Wisp: Cloudy, thread-like inclusions often formed by intersecting pinpoints.

- Crystal: Mineral crystals trapped inside the diamond can vary in colour and size.

- Needle: Long, thin inclusions resembling a needle.


Different types of inclusions impact the diamond's clarity and visual appeal to varying degrees. While some inclusions are minor and not visible to the naked eye, others can significantly affect the diamond's appearance and durability.





Overall Brilliance and Fire


Brilliance refers to the white light reflected from the diamond, while fire describes the dispersion of light into various colours. Together, they determine the diamond's visual performance and attractiveness. High brilliance and fire indicate excellent cut quality and proper proportions, making the diamond more appealing and vibrant.





Certification Type


Certification type refers to the grading report provided by an independent gemological laboratory, such as GIA (Gemological Institute of America), AGS (American Gem Society), or EGL (European Gemological Laboratory). These certifications provide detailed information about the diamond's characteristics, including carat weight, colour, clarity, cut, and more.


GIA (Gemological Institute of America) reports are widely regarded as more reliable than those from EGL (European Gemological Laboratory), IGI (International Gemological Institute), and other laboratories. This reputation stems from GIA's stricter and more consistent grading standards, which result in more accurate and trustworthy diamond assessments. Additionally, GIA's status as a non-profit organization focused on research and education, as opposed to the for-profit nature of labs like EGL and IGI, contributes to its credibility. The commercial interests of for-profit labs can potentially lead to more lenient grading practices. These factors combined have established GIA as the gold standard for diamond certification in the industry, providing greater confidence to both buyers and sellers in the global diamond market.


A reliable certification ensures the diamond's quality is accurately represented, giving buyers confidence in their purchase. Layla Kaisi Collection strictly sources diamonds with GIA reports only.





In conclusion, navigating the world of diamond shopping requires more than just a basic understanding of the 4Cs. While cut, clarity, color, and carat weight form the foundation of diamond evaluation, savvy buyers should also consider factors like fluorescence, polish, symmetry, and depth percentage.


These additional characteristics play crucial roles in a diamond's overall beauty and value. By familiarizing yourself with these terms and their implications, you'll be better equipped to make an informed decision when selecting your perfect diamond. Remember, each of these factors contributes to the unique story and brilliance of your chosen stone.


At Layla Kaisi Collection, we're committed to guiding you through this journey, ensuring we meticulously hand select a diamond that not only meets the highest quality standards - the LKC Standard - but also resonates with your personal style and preferences.

Image of Ophelia Mason author for the Layla Kaisi Collection Journal

Ophelia Mason

Ophelia Mason is a writer, content creator, and author for the Layla Kaisi Collection Journal. She transcribes the beauty of artistically handmade jewellery. She is passionate about sharing the stories woven through each design and retelling the moments captured in each piece in imaginative detail. She has an eye for creative harmony and an appreciation for individual reflection in the form of unique jewellery.

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