DIAMONDS: THE DEEP CUT

Diamonds are often seen as some of the most expensive natural materials on Earth—but what actually determines their high price tags? Most people have heard of the 4 C’s—Carat, Cut, Color, and Clarity—which collectively define a diamond’s quality and value. Each of these factors plays a distinct role, and understanding them helps explain the wide variation in both price and appearance across diamonds.

Having worked in the Diamond District for half of a decade, I’ve noticed a significant gap in public understanding when it comes to evaluating diamonds. Since many people will purchase a diamond at some point in their lives—often for meaningful occasions—it’s worth breaking down what truly influences the value of a diamond.

Let’s start with the anatomy of a diamond, so we can dive into this like experts. Below is a diagram explaining some diamond jargon that we will be using throughout this article. 

 

CARAT

Carat refers to a diamond’s weight. In general, a higher carat weight means a larger diamond and, therefore, a higher price. However, weight does not always translate directly to visible size. Some diamonds carry more of their weight in their depth (a deeper pavilion), making them appear smaller from the top. Others distribute more weight across the surface (a larger table), creating what’s known as a “spready” stone—one that appears larger than its actual carat weight might suggest.

As carat weight increases, price rises exponentially, not just because of size but also due to rarity. Larger, gem-quality diamonds are far less common. Pricing is also structured in tiers (e.g., 1.00–1.49, 1.50–1.99 carats, 2.00-2.99 carats, etc.), and diamonds approaching the upper end of a tier often carry a premium. For example, a 2.95-carat diamond may be priced within the 2.00–2.99 range but appear similar in size to a 3.00-carat stone—making it particularly desirable and valued higher.

CUT

Cut is a more complex factor. It refers not only to the shape of the diamond, such as Round Brilliant, Oval, Pear, Emerald, Marquise, Old Mine or Old European, but also to how well the diamond has been cut and finished. Shape can influence price based on demand; for instance, elongated shapes like Ovals and Old Mines are currently very popular and may command higher prices. This Art Deco 1.60 Carat Old Mine Cut Diamond Octagonal Ring with Onyx features a perfect example of a stunning elongated Old Mine cut diamond.

 

Beyond shape, cut quality includes symmetry and polish. Symmetry refers to how well the diamond’s facets align, while polish describes the smoothness of its surface. Both are graded on a scale from Excellent, Very Good, Good, to Poor. Well-cut diamonds maximize light performance, producing greater brilliance (white light reflection) and fire (colored light dispersion). Poor symmetry or polish can diminish these effects. 

These cut characteristics also determine how a diamond handles light based on its proportions. A very shallow or overly deep diamond will not reflect light as effectively, reducing sparkle. For example, in round brilliant diamonds, an optimal table percentage typically falls between 53% and 58%, while depth is ideally between 59% and 62.6%. These proportions help balance visual size and brilliance.

There are instances where diamonds are purposefully cut flatter or thicker, especially when talking about antique jewelry. Rose cut stones, which originated in the 16th century and can be found in a lot of our antique pieces, are purposefully flat to give a more subtle sparkle. This Edwardian 1900s 2.65 Carat Pear-Shaped Diamonds Ring features two exceptional Rose cut Pear Shaped Diamonds, which is truly a rarity.

 

There are also instances, like in Old Mine cut diamonds, where diamonds were cut deeper. Back in the day, diamonds were cut to sparkle in candlelight rather than modern lighting. These deeper Old Mine cut diamonds had chunkier facets which made for a more romantic sparkle. Old Mine cut diamonds also have the ability to create what is called a Kozibe effect. This is when the cut culet reflects within the diamond’s table creating a mirror effect, which almost makes it look like a disco ball inside the diamond. This Edwardian 3.00 Carat Old Mine Cut Diamond Engagement Ring has an Old Mine cut diamond that has a Kozibe effect that is almost visible in the pictures, too!

 

COLOR

Next is color. Diamonds are graded on a scale from D to Z, with D representing completely colorless stones and Z showing noticeable yellow tint. Colorless diamonds (D–F) are the rarest and most expensive, followed by near-colorless (G–J), with increasing warmth visible beyond that range. Below is a color grading scale to visualize the difference between color grades.

After Z colored diamonds comes Fancy Yellow diamonds, which are graded and valued on a completely separate scale. Other Fancy colored diamonds can be found in nature as well, such as blue, green, red, and more colors. 

Unlike cut, color has a more direct and measurable impact on price, with value decreasing with each diminishing color grade. The price change per change in color grade also varies across carat weight and clarity levels. Larger carat weight diamonds have a greater increase in price per whiter color grade. While whiter diamonds have been traditionally more desirable, warmer toned diamonds have been on the rise lately. Champagne and desert diamonds set in yellow gold settings have taken the spotlight following some celebrity engagements, especially antique engagement rings of the sort! Victorian rings, like this Victorian 1.20 Carat Old Mine Cut Diamond Engagement Ring, are a perfect example of this.

 

CLARITY

Last, but certainly not least, the clarity of a diamond will have a substantial impact on a diamond’s value and appearance. The clarity of a diamond refers to the number, position and visibility of imperfections that occur within a diamond and blemishes that occur on the outside of a diamond. These imperfections can include natural feathers, pinpoints, crystals, needles, cavities, etc. that occur when the diamond is being formed. Blemishes, like bruises, chips, etc., can occur when the diamond is being cut and polished. Clarity is graded from Flawless (F) to Included (I). Each clarity level is broken down below:

 Flawless (F)

• No inclusions (internal flaws)
• No blemishes (surface flaws)
• Perfect under 10× magnification

Internally Flawless (IF)

• No inclusions
• May have very minor surface blemishes

Very Very Slightly Included (VVS1, VVS2)

• Extremely tiny inclusions or blemishes
• Very difficult to see, even for a trained grader at 10× magnification

Very Slightly Included (VS1, VS2)

• Small inclusions
• Visible under 10× magnification, but still minor

Slightly Included (SI1, SI2)

• Noticeable inclusions
• May be visible to the naked eye, but usually not obvious—especially to untrained observers

Included (I1, I2, I3)

• Clear, visible inclusions and blemishes
• Imperfections are easily seen and may affect appearance and durability

Similar to color, with each clarity grade, there will be a precise change in the price. This decline will also vary based on color and carat weight.

Ultimately, a diamond’s value is not determined by a single characteristic, but by the interplay of all four C’s. Carat may catch the eye, but cut dictates brilliance; color influences purity, while clarity affects overall visual perfection. The key to making an informed purchase lies in understanding how these factors work together and deciding which qualities matter most to you. In general, I always recommend choosing a diamond that is in the range of G-H color and VS1-VS2 clarity. This is the best “bang for your buck” diamond, because this is still a high quality diamond, but not as costly as a flawless diamond. There is no one “perfect” diamond—only the diamond that best balances beauty, quality, and value for the individual buyer. By looking beyond surface impressions and understanding the fundamentals, buyers can approach their purchase with confidence and clarity, ensuring that their investment is both meaningful and well-informed.