Diamond Quality Explained

Diamond Quality – Basics

What defines diamond quality? Opinions vary. Diamonds with “low” colors and clarities can be far more breathtaking and visually desirable than certain diamonds with “high” colors and clarities.

PriceScope Pointer: Color and clarity may be considered diamond quality factors, but the way a diamond is cut undeniably has the most influence on its beauty.

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Diamond Quality Described

Quality is defined as the standard of something when measured against other things of a similar kind; the degree of greatness. However, when measuring how “great” one diamond is, compared to another, there’s no standardized diamond quality chart.

Diamonds are valued for both aesthetic appeal and emotional symbolism. The way a diamond is cut unarguably has the most influence on its aesthetic properties, but what greatness aspect can we tie to symbolism? Most couples would reject the notion that the symbols of commitment and love they exchanged are less “great” than other diamonds.

diamond quality - couple with diamond

Popular Belief System

The diamond mining industry classifies opaque, heavily included rough diamonds as “industrial quality” and clear, less included diamonds as “gem quality.”

Many jewelers, including leading luxury brands, extend this mining concept to the diamonds used in jewelry. In this popular belief system, diamond quality is defined by three of the 4Cs: Colorless diamonds are considered higher in quality than near colorless or slightly tinted diamonds. Flawless diamonds are considered higher in quality than those with clarity characteristics and a Super-Ideal cut diamond lands higher on a diamond quality chart than one with Excellent cut.

Isn’t this diamond rarity?

No. This belief system doesn’t extend to carat weight: a 1.00 carat diamond with high color and clarity is perceived as higher in quality than a heavier diamond with low color and clarity, although higher carat weights are exponentially rarer. Simply put, according to this popular belief system, less nitrogen (nitrogen causes yellow tint) and fewer clarity characteristics imply better quality at any carat weight.

How does that make sense?

It’s effective marketing. Diamond shoppers who adopt belief system are motivated to spend extra money on higher perceived diamond quality (more expensive colors and clarities) at any carat weight they can afford. It also makes sense for shoppers seeking collection quality diamonds, which have historically held and increased in value best over time.

PriceScope’s 1-5 star ratings are categorical comparisons with the most thorough, consumer-focused online diamond and jewelry vendors, in categories, we believe reflect our experienced consumer community’s values. Check out PriceScope Jeweler Reviews

Collection Quality Diamonds

Collection quality diamonds are those with the purest natural color and clarity grades. These diamonds have historically held and increased in value best over time, especially auctionable diamonds of significant carat weight and value. Collection quality diamonds have special status in the eyes of many diamond professionals, collectors, enthusiasts, and auction houses.

diamond quality - tiffany solitaire

Collection Color and Clarity

In terms of color and clarity the pinnacle of collection diamond quality is D Flawless, closely followed by D Internally Flawless. Any combination of D color, E color or F color with Flawless, Internally Flawless, VVS1 or VVS2 clarity falls into the collection category of diamond quality.

No Fluorescence Allowed

The presence of fluorescence will knock a diamond out of the collection category. This is because fluorescent diamonds trade at discount, usually in proportion to the strength of fluorescence. This is especially true for colorless diamonds.


In terms of certification, diamonds of collection quality are typically graded by a top-tier laboratory enforcing internationally accepted standards. Diamonds of significant carat weight and highest value are historically supported with a grading report from the Gemological Institute of America (GIA) when sold at auction.

Craftsmanship: Polish and Symmetry

Fancy shaped diamonds must have Very Good to Excellent grades in both polish and symmetry. Round brilliants must have Excellent in both polish and symmetry (or Ideal, if graded by the American Gem Society).

Craftsmanship: Diamond Cut

Cut Grading is a relatively new consideration for collection quality diamonds. GIA, the most frequently used laboratory for auctionable diamonds, only began issuing a cut grade for round brilliant diamonds in 2006. Prior to that, only polish and symmetry were assessed. Today many traders and collectors only consider a round brilliant diamond to have collection quality if it has Excellent grades in all three assessments: polish, symmetry and cut (or Ideal grades, if graded by the AGS).

GIA Report Update Advisory

Some owners and brokers of round brilliant diamonds originally graded by the GIA prior to 2006 have been unpleasantly surprised when sending those diamonds back for an updated grading report.

Diamonds are usually planned and fashioned to yield as much weight from the rough material as possible. When collection quality rough crystals are discovered the biggest producers tend to seize that material in order to produce fat collection quality diamonds primarily cut for highest carat weight, maximizing their value. Before 2006 the GIA was not issuing a grade for cut, so there was no penalty for rounds cut with angles which egregiously added weight in the belly of the diamond at the expense of beauty.

The GIA cut assessment is now applied to all round brilliants and, although the system is extremely permissive, older diamonds may not receive the post-2006 Excellent cut grade, knocking them out of the collection quality category. It may be possible to have the diamond recut to proportions which will receive the Excellent grade but, depending on specifics, the expense of weight needed to improve the diamond could drop it into a lower pricing category.


Collection quality diamonds come in all shapes. At lower weights, round brilliant diamonds trade for higher values than similar diamonds in fancy shapes but, as weights exceed 10 carats, that value gap becomes bridged. Historic collection quality diamonds of extremely high weights, in the hundreds of carats, may be faceted in unique ways, without conforming to any traditional shape.

If you’re looking to buy loose diamonds online, use our special tools to reveal the best cut quality diamonds! Start your diamond search and choose from over a million loose diamonds for sale. Use our filters to find either natural or lab diamonds, as well as fancy color diamonds. 

Intermediate Diamond Quality

Let’s Get Real

In any analysis of what defines “diamond quality” there’s an inconvenient truth which must be acknowledged:

Nature versus Nurture

Humans developed extremely rigid standards for judging the Cs of “diamond nature” (how mother earth grew a diamond) but have scandalously loose standards for judging the Cs of “diamond nurture” (what humans did to prepare it for sale).

The Cs of Nature

Nature gave each diamond its color, clarity, and raw carat weight a billion years ago. Excluding controversial treatments and enhancements, a diamond’s color and clarity cannot be changed. They are the result of chemicals and elements far below the earth where heat, pressure and carbon came together in just the right combination to grow a diamond. Mother Earth is responsible for every rough diamond’s color, clarity, and raw carat weight. These three Cs are 100% attributable to nature, meaning perceived rough diamond quality can be 100% connected to rarity.

diamond quality - planet earth

The Cs of Humans

Humans takes nature’s creation and “nurture” it to completion. Humans are 100% responsible for a diamond’s two final Cs: its cut and its finished carat weight. The reason those last three words are bolded is because the humans in charge rarely focus on “diamond quality” (quality cutting). They instead focus on how to keep the highest possible finished carat weight after cutting, often at the expense of beauty, in order to maximize profits.

diamond quality - greedy person

PriceScope Pointer: Read this real world information, to learn how 60% of round brilliants receive the “Excellent” diamond cut grade, despite having visible character and quality differences

The Inconvenient Truth about Diamond Quality

Humans created extremely strict diamond quality standards for what Mother Nature did. The majority of people can’t tell D color from G color unless the diamonds are analyzed side by side and the D-Z color “quality” is divided into 23 grades. Then you have the clarity category, where the highest six grades all look the same to the naked eye, but cost more the higher you go, based on invisible differences in perceived “color quality.”

Now consider the diamond quality standards humans created for humans. Cut grading is scandalously loose. More than 60% of diamonds graded by GIA earn their highest cut grade. As a result, quality is not the focus of most diamond producers when cutting. Instead, they focus on preserving the most carat weight from the rough crystal. They do this by making cutting angles as wide as possible, resulting in a heavier but darker, less lively diamonds. Since most grading laboratories are extremely loose when grading grade, there is no motivation to break this cycle. It’s not an exaggeration to say most diamond shoppers have probably never seen a diamond cut to have the best brightness and sparkle possible. They are extremely rare.

Fighting the Good Fight

A small number of diamond producers do focus on cutting diamonds for beauty as their top priority. However, these producers must bid for rough diamond parcels against other producers who are willing to preserve more weight from the same raw material, at the expense of beauty. This means the quality focused producers must bid as much (or more) to acquire rough diamond parcels, ultimately yielding smaller finished diamonds. Those diamonds are in short supply but are consistently more beautiful than average steep deep diamonds.


Cutting undeniably has the most influence on diamond beauty. The quality of cutting should undeniably rank first in how diamond quality is defined. Yet this all-important diamond quality factor, which is entirely under the control of humans, is the one factor that “gets a pass” and is not held to a meaningful standard.

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