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The 4 Cs of Diamonds: A Guide to Understanding Diamond Quality

When it comes to diamonds, there are a lot of terminologies that many don’t understand—especially when selecting a diamond for the first time. The four Cs (short for color, cut, clarity, and carat weight) are key components you must consider before purchasing your diamond to fully understand its quality. Knowing what each of these categories represents can help guide you through the process of selecting the perfect diamond according to your budget, needs, and individual style preference – this is why understanding the 4Cs of diamonds is so important!

However, we would like to note that it is always a good idea to consult a professional jewelry appraiser to learn more about your diamonds.

In this blog post, we’ll provide an overview of how to assess each ‘C’ to ensure you get exactly what you’re looking for.

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Background on 4 Cs

The 4 Cs of Diamonds

Prior to the middle of the 20th century, there were no agreed-upon standards or evaluation diamonds. The Gemological Institute of America (GIA) set the first standard for characterizing diamonds, which is now worldwide accepted: Color, Clarity, Cut, and Carat Weight.

The 4Cs of Diamond Quality is the global standard for evaluating the quality of any diamond everywhere in the world.

The introduction of the Diamond 4Cs marked two significant advances: diamond quality could now be communicated in a global language, and diamond buyers could now understand exactly what they were purchasing.


Carat is a unit of measurement for the diamond’s actual weight.

According to the GIA, one carat is equivalent to 0.2 grams, or around the weight of a paper clip. Obviously, the greater the carat weight, the higher the price. Because no two diamonds are similar, the carat should be treated as a guide, as it only indicates the stone’s weight and not its real size. Five oval diamonds, each weighing exactly 2.00 carats, with identical color, clarity, and cut, will have slightly varying sizes and shapes.

A diamond carat is divided into 100 points, so a diamond with 50 points weighs 0.50 carats. However, a stone of a given weight may appear larger than its carat weight indicates due to its proportions (measured in millimeters). For instance, it is possible to discover a diamond that weighs 2.0 carats yet appears to be closer to 2.20 carat stone. Essentially, you are purchasing a stone that appears larger without incurring the additional expense associated with a heavier weight.


The only diamond component not impacted by nature is the cut.

This is the most crucial of the 4Cs. This criterion refers to the quality of the diamond’s cut, not its form or size (although these terms can be interchanged), and how well the stone is faceted, proportioned, and polished.

This also impacts the interaction of the diamond with light. The diamond’s brilliance, which is its capacity to return light to the eye, is determined purely by its cut (color and clarity have no impact). Visually, the first C to consider for any diamond form is the cut, followed by color and, least essential, clarity (as long as the diamond has no eye-visible imperfections).

The GIA system classifies diamond cuts as Excellent, Very Good, Good, Fair, or Poor.

The size and proportion of a diamond can significantly affect its appearance, particularly for elongated forms such as marquise, oval, radiant, emerald, and pear. Maintaining a well-balanced length-to-width ratio scale might make the stone appear larger. Specifically, elongated shapes come in a number of size ratios, defined by both cut and carat weight. However, for the best diamonds, keeping within the Excellent to Very Good cut range is essential.


This C refers to the number of inherent flaws, known as inclusions, present in the diamond and whether they are visible to the naked eye. The GIA diamond grading scale ranges from Flawless (F) to Included (I) (I). However, a diamond does not need to be Flawless or Very, Very Slightly Included (VVS) to appear flawless and inclusion-free. It’s all about how clean the diamond appears to the naked eye. This is what amazes people the most when they encounter diamonds in person. In fact, if an SI1 (Slightly Included) diamond seems flawless to the naked eye, there is no discernible difference between it and a VVS1 (Very, Very Slightly Included) diamond of the same carat, color, and cut, minus tens of thousands of dollars.

There is no reason to go above VS1 clarity for any diamond shape outside emerald and the Asscher, where inclusions can be easily seen. For all other shapes, starting with SI1 [Slightly Included] clarity and above, there should be no discernible flaws to the human eye. Occasionally, even SI2 diamonds can be exceptionally eye-clean, but in general, stay with SI1 and above.

It is essential to strike a balance between color and clarity to get the most out of a diamond for the least amount of money. This balance varies depending on the form of the diamond, but you can save money without sacrificing quality by staying on the higher end of the color scale and the lower end of the clarity scale, so long as there are no visible inclusions.

Read More: Understanding Diamond Clarity [Comprehensive Guide]


For diamonds that fall in the category of colorless to near-colorless range, assessment of the color of a diamond of gem quality is based on the absence of color comparable to a drop of pure water. Less color in a diamond will increase its value for color.

The GIA developed a D-to-Z scale that is commonly used in the jewelry industry as far as colorless diamonds are concerned. The scale begins with the letter D, which is considered colorless, and progresses to the letter Z, which has an increasing color presence. Numerous of these color distinctions are so minute that they require a trained eye (an experienced gemologist) and a collection of master stones to distinguish.

In its most basic form, diamond fluorescence is the effect of ultraviolet (UV) light on a diamond. Sometimes, when you stand under blue or ultraviolet light, your whites become brighter, or your teeth appear to glow. Diamonds in the color range D to H with a bluish fluorescence are frequently regarded as less desirable by the diamond trade. Bluish fluorescence might give these diamonds a hazy or greasy appearance, but only if the fluorescence intensity is exceedingly strong. However, not all diamonds with intense bluish fluorescence appear oily, and they may sell for less than diamonds without blue fluorescence. Vendors normally sell a diamond with fluorescence for 5 to 10% less if all other factors are equal.

It is essential to ensure that the color grade is accurate because the value difference between colors can be substantial on price.

Balancing the 4Cs

Each of the four C’s contributes to a diamond’s overall beauty and individuality. However, a diamond should be considered an organic whole. Because the human eye has difficulties distinguishing individual diamond characteristics, such as Clarity or Color, it is essential to understand how the 4 C’s interact.

Reach out to Willyn Villarica Jewelry

Willyn Villarica is your trusted partner for diamond-grading services, catering to clients around the globe. Our expertise and commitment to excellence ensure accurate and reliable assessments of your precious gemstones. It’s important to note that while we offer our services worldwide, clients are responsible for covering all travel expenses. Don’t miss out on the opportunity to have your diamonds expertly graded by Willyn Villarica. If you need a professional jewelry appraiser, reach out to us at admin@willynvillaricajewelry.com for inquiries or to schedule appointments. You can also connect with us on our official Facebook (Willyn Villarica Jewelry) and Instagram (@willynvillarica_jewelry) accounts. Need immediate help? Dial +63279497547. As one of the few certified gemologists in the Philippines, a graduate of the GIA Graduate Gemologist® program, and the only NAJA-recognized Filipino appraiser, you know you and your jewelry are in good hands with Willyn Villarica Jewelry.

  • Willyn Villarica

    Willyn Villarica, a third-generation jeweler from the Philippines, brings a wealth of expertise to the world of gemology and jewelry appraisal. As a licensed Graduate Gemologist, accredited by the prestigious Gemological Institute of America, she is not only a master of her craft but also holds the distinction of being the first Filipino member of the National Associ...

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