Expertise you can trust: Klara Allen is known for its award-winning jewelry designs and seamless, innovative shopping experience. This Klara Allen diamond guide explains how the 4 C's of diamonds — cut, color, clarity, and carat — determine a diamond's quality grade. All Klara Allen guides are meticulously researched and reviewed by our certified gemologists, content, editorial, and brand teams before publication to ensure industry-leading excellence and accuracy. 

4 C’s of Diamonds Charts

Created by the Gemological Institute of America (GIA) in the 1940s, the 4 C's — cut, color, clarity, and carat — serve as the universal standard for assessing diamond quality. Each C represents a distinct quality attribute, measured on its own scale: 

  • Cut: Graded from Excellent to Poor on the GIA scale and Ideal to Poor on the International Gemological Institute (IGI) scale 
  • Color: Graded from D (colorless) to Z (light yellow or brown) 
  • Clarity: Graded from Flawless (FL) to Included (I3) 
  • Carat: Measured in metric carats, where one carat equals 200 milligrams

The 4C’s of Diamond

Choosing a diamond is an exciting step, and we understand you want to feel confident about your selection. But understanding and navigating the realm of diamonds can be daunting without proper guidance. That's where the 4C’s come in handy. The 4C’s – cut, color, clarity and carat, are your key to understanding a diamond’s beauty, quality and value. Considering these factors will help you find a diamond that sparkles brilliantly and fits your budget and taste perfectly.

The 4C’s of Diamonds is an industry standard, fundamental framework put forward by the Gemological Institute of America (GIA) in the 1940s. It stands for cut, color, clarity and carat weight of a diamond. Each of these characteristics are graded and documented by professionals. As a universal scale to assess and determine the quality of diamonds, this framework allows enthusiasts and buyers alike to define, assess and appreciate diamonds with confidence and consciousness.

Cut

A diamond's cut is the artistry behind the stone’s proportions, facet arrangement and overall symmetry. These elements work together to influence how the stone interacts with light. The cut is one of the most important factors determining a diamond's brilliance, fire and sparkle. The quality of a diamond’s cut is graded on a scale from Excellent to Poor. So, the better the cut, the more valuable your diamond will be and the more beautifully it will dance with light.

Color

Diamond color is about the absence of color and how close a diamond is to be colorless. The diamond color scale goes from D to Z, with D representing completely colorless stones and Z indicating a faint yellow or brown tint. The closer a diamond gets to D on the scale, the rarer and more valuable it becomes.

Clarity

Diamond clarity refers to its purity and how clear it naturally is. This implies the absence of tiny flaws known as inclusions within the stone and imperfections on its surface which are called blemishes. Clarity is graded on a scale ranging from Internally Flawless to Included, and it impacts a diamond's beauty and rarity.

Carat

Carat is a universal measurement unit of a diamond’s weight. One carat is approximately equivalent to the weight of a paperclip. Carat is the most important element affecting the price of a diamond as it has to do with its mass and size.

Diamond Shapes

Diamonds sparkle in more ways than one. They come in a variety of geometric forms, referred to as shape and with each adding a distinct personality to the stone. Each diamond shape has its own unique set of requirements and technical considerations. The shape you choose can therefore dramatically affect the overall look and feel of your stone.

It’s important to note that the shape and cut are two different aspects. Cut describes how the facets are arranged on the inside of the diamond, which impacts its brilliance greatly. Shape, on the other hand, refers simply to its outline. The most popular choice is the round brilliant diamond that is known for its classic fire and sparkle. But there's a whole world of fancy shapes to explore, like emerald, oval, radiant or marquise. You can learn more about each shape and how it can influence the overall design of your ring in our comprehensive engagement ring guide. 

Shop Diamonds by Shape

Diamond Size

Diamond size — distinct from carat weight though often mistakenly used interchangeably — refers specifically to a gem's physical dimensions and visual presence, most commonly measured in millimeters across the widest points. 

When evaluating size, consider actual millimeter measurements rather than relying solely on carat weight. A standard 1-carat round brilliant typically measures about 6.5mm in diameter, while a well-cut oval or marquise of the same weight may appear larger due to their elongated shape and greater spread. 

For engagement rings, the setting style further influences perceived size — halos (small diamonds surrounding the center gem) can make a diamond appear larger, while cathedral settings elevate the gem for greater prominence.

Types of Diamonds

Natural Diamonds

Natural diamonds form deep within the Earth under extreme conditions of heat and pressure over billions of years. They are comprised of nearly 99.95% carbon — making diamonds the only gemstone constructed of a single element. They are the hardest naturally occurring materials found on Earth and gem-quality diamonds are one of the most sought-after. Because of their limited quantity, natural diamonds have been cherished for their enduring value and passed from generation to generation.     

Lab Diamonds

Lab diamonds are optically, chemically, and physically the same as natural diamonds. Their difference lies only in their origins — natural diamonds form within the Earth, and lab diamonds are grown by professionals with specialized equipment. Another difference is cost; as lab grown diamonds are less rare than natural diamonds, they often come at a much more accessible price.

4 C’s of Diamonds Tips: Finding Your Perfect Combination

Finding your dream diamond requires balancing the 4 C’s with your personal priorities. Here are a few tips from our Klara Allen gemologists to help guide your decision: 

1. Master the 4 C's. To discover the ideal diamond for you, develop an understanding of how each factor affects a diamond's appearance and value. Then, determine which characteristics matter most to you personally. If exceptional brilliance is your priority, emphasize cut quality above all else. If impressive size makes the greatest impact for you, you might strategically compromise on color, cut, or clarity to get a greater carat weight. Remember that there's no universally "correct" combination — your aesthetic preferences should guide the way. 

2. Target value "sweet spots". Certain grade combinations offer superior value by delivering an excellent appearance without commanding premium prices:  

  • Color: H-J diamonds present exceptional value, appearing near colorless to the naked eye 
  • Clarity: Depending on carat weight and shape, VS2-grades can appear "eye-clean" without the substantial premiums of higher clarity grades 

3. Select your signature shape. Round diamonds offer unmatched brilliance and traditional appeal, but typically command higher prices than fancy shapes, which can provide better value and a distinctive appearance. Choose the shape that resonates with your personal style, whether you're drawn to timeless rounds or the unique character of fancy shapes like oval, cushion, or emerald. 

4. Ensure proper certification. Your diamond should come with a comprehensive grading report from a respected independent laboratory such as GIA, IGI, HRD, or GCAL. These certificates verify your diamond's authenticity and provide objective documentation of its quality characteristics. Please note that all Klara Allen center stones are certified.