Is Cut Important in a Diamond?

Sharif Khan
Sharif Khan
Last Updated    EST 

A diamond's cut is one of the most critical factors when determining a stone's overall brilliance, fire, and scintillation. It is also the only one among the 4Cs that relies on human craftsmanship and machinery, setting it apart from the other 3Cs governed by nature. Thus, it becomes imperative to familiarize oneself with the intricacies involved in creating an excellently cut diamond. This knowledge empowers informed decisions and allows for optimal utilization of a given budget.

Indeed, the cut assumes a pivotal role in assessing a diamond's value. While the GIA exclusively assigns cut grades to round diamonds, the AGS extends its evaluation to both round and other fancy-shaped diamonds. The former employs a grading scale spanning from excellent to poor, while the latter encompasses a range from Ideal to Poor. Our website serves as a repository of comprehensive insights into evaluating the cut across various diamond shapes. To illustrate, if you're keen on determining the cut grade of a round-cut diamond, I strongly recommend consulting the dedicated page on our website.

During the process of diamond evaluation, significant attention must be directed toward the cut's quality – a fundamental aspect. While the other three Cs (color, clarity, and carat) certainly hold importance, the cut claims precedence due to its role in determining the diamond's sparkle, the very essence of diamond allure. A meticulously executed cut ensures that facets are properly proportioned and angled, effectively reflecting and refracting light, thus harnessing positive effects and preventing premature light escape from the stone's rear. A diamond characterized by precise cutting emanates brilliance and charm, in stark contrast to a poorly cut counterpart that appears lackluster and bereft of vitality.

To assess a diamond's cut, use the innovative Jame Allen's 3D 360 Degree 40X Video technology.

Assessing the Cut

diamond cut chart

Certain diamond cutters have a tendency to salvage rough diamonds by implementing deeper cuts. It is crucial to understand that the purchase of a deep-cut diamond might not necessarily align with the best course of action for you. For instance, the visual and dimensional equivalence between a 0.80-carat diamond and a 1-carat diamond can be achieved if the latter is cut with increased depth. Presented below are a two examples that illustrate the concept of deep-cut diamonds.

diamond depth shallow

The second important point while selecting a slightly deeper cut diamond with the right proportions would be to look at its overall dimensions in millimeters. For example, you might come across a round-cut diamond with 64% depth. However, if it has a thinner girdle and a larger table size, it might make up for the lost size. Thus, one of the best ways to analyze the visual appearance of a stone is to look at its dimensions in millimeters, as shown below: 

Round 1ct. (Actual Examples)

Option 1) Deeply cut:

5.93-6.02x4.17mm – Table 55% Depth 68.8%

Option 2) Excellent Cut:

6.57-6.59x3.92mm – Table 58% Depth 61%

Option 3) Very Good Cut with 64% Depth:

6.30-6.34x4.03mm – 64% Depth Table 57%

Princess Cut 1ct. Square (Actual Examples):

Option 1) Deeply Cut:

5.03x5.01x4.00mm – 80% Table and 80% Depth

Option 2) Excellent Range:

5.47x5.39x3.87mm – 70% Table and 71% Depth

Option 3) Slightly Deep Cut:

5.48x5.37x4.08mm   – 71% Table 76% Table.

The table imparts two significant insights:

  1. In round cut diamonds, a slightly deeper cut can lead to a smaller diamond, contingent on the stone. This difference is observable in millimeters, comparing excellent cut with very cut diamonds having a depth of 64%.
  2. In the case of fancy cut diamonds, this principle may not always hold true. It's possible to acquire a slightly deeper cut diamond with the same or larger millimeter dimensions as one with ideal proportions. It's important to note that fancy cut diamonds are crafted differently, and the establishment of ideal proportions by the GIA for such cuts is still under consideration. Therefore, opting for a slightly deeper fancy cut diamond, provided it has appropriate dimensions and a commendable table, could be a prudent choice if the price is right.

This leads us to the third critical aspect of diamond cut. While the cut holds importance, it's crucial not to excessively emphasize it, especially if budget constraints are a factor. While observing a diamond in person, the disparity between a very good and excellent cut is minimal. The GIA maintains strict criteria, and a minor discrepancy could result in a diamond being categorized as a very good cut rather than an excellent one. Therefore, if the depth, table, and other proportions align well, there's no hesitation in opting for a very good cut diamond. This advice extends to the polish and symmetry level decisions for both round and fancy-cut diamonds. While an excellent cut is desirable, it might not be justifiable if the associated price increase is substantial.

The fourth and final takeaway is that a detailed examination of cut proportions and specifics is essential for each stone, based on its shape. It's crucial to recognize that the guidelines for selecting a round diamond cannot be uniformly applied to a radiant cut diamond. To ensure precision, consult our comprehensive guides tailored to each specific shape, which will provide you with the exact criteria to seek and how to evaluate proportions:

Round Cut DiamondPrincess Cut DiamondOval Cut DiamondCushion Cut DiamondEmerald Cut DiamondRadiant Cut Diamond,  Marquise cut Diamond, and Asscher Cut Diamond.

Determining the Cut Grade

In our recent publication, we delved into the intricate process of determining brilliance in diamonds. This article comprises two distinct sections, each presenting viewpoints that appear contradictory. The initial segment outlines the optimal proportions for both round and non-round-cut diamonds. However, the subsequent portion delves into the GIA's findings, which indicate that diamonds need not adhere to rigid parameters or proportions to achieve exceptional brilliance. Additionally, it highlights that diamonds cut with varying proportions can still attain an equivalent level of brilliance.

In essence, the matter of diamond cut is multifaceted, and for the average consumer, it's advisable to align with the industry's established norms. When considering round-cut diamonds, it's prudent to prioritize the GIA's cutting grading. Alternatively, you can make use of the summarized proportions provided in the aforementioned article for a more streamlined approach.

diamond cut anatomy


The term "diamond cut" might come across as quite technical at first glance. To someone unfamiliar with the intricacies of the diamond market, it could conjure images of slicing or shaping a diamond with a blade. However, its significance reaches much deeper. The cut of a diamond encompasses factors such as symmetry, proportions, and polish, all of which contribute to its overall character. Each of these elements plays a pivotal role in crafting a diamond's appearance, collectively falling under the umbrella term "cut."

Never underestimate the pivotal role of cut when embarking on a diamond purchase. It stands as the most crucial attribute that significantly impacts a diamond's market value. The arrangement of a diamond's facets determines its symmetry and cut. As the term suggests, "polish" refers to a diamond's smoothness and shine, directly influencing its sparkle and allure. This characteristic endows a diamond with the remarkable ability to reflect light, resulting in three captivating effects: brightness, fire, and scintillation. Brightness involves the diamond's inherent capacity to reflect white light, fire creates the mesmerizing rainbow play of colors, and scintillation, both quantitatively and qualitatively, showcases the diamond's skill in producing patterns of light and shadow through reflections.

There's sometimes confusion between a diamond's cut and its shape—the form into which a rough diamond is meticulously carved. Diamonds can assume various shapes through steep, fancy, or mixed cuts, based on the original structure of the raw diamond. Cut decisions can also be influenced by factors such as the popularity of specific shapes, internal features or flaws of the raw diamond, and the desire to retain the diamond's carat weight. Every diamond cutter aims to achieve the optimal final product through a cut that minimizes wastage of carat weight, while maximizing brilliance and minimizing light leakage.

Among the 4Cs of a diamond, assessing cut poses the greatest challenge for customers. It's evaluated through various standards, with the GIA offering a straightforward system consisting of five grades: Excellent, Very Good, Good, Fair, and Poor. A higher cut grade translates to a higher diamond value. It's worth noting that the blend of empirical and mathematical aspects during the process can yield a stunning diamond that sparkles brilliantly. Technology is also stepping in, reducing the reliance on manual craftsmanship for the cutting process in various parts of the world.

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