How To Assess the Quality of Colored Gemstones (vs. Diamonds)

Many jewelry buyers will have at least a vague idea of how we might go about assessing the quality of a colorless diamond…but what about assessing the quality of colored gemstones, including colored diamonds?

What might that entail?

While the 4Cs GIA grading system is applied to the pick n’ mix of colored gemstones, the process of evaluating the quality is often far more complex than you might first assume.

Assessing the Quality of Colored Gemstones With Loupe

In today’s article, we are going to look at everything that is taken into consideration when determining the quality of a colored gemstone. I think, however, it is perhaps best by starting with what we know best and taking a look at how we grade a colorless diamond.

Quality assessment for colorless diamonds recap!

Alright, most of us are aware of the 4Cs grading system to some extent. For those who aren’t, we at least know enough to understand that when we are looking for a quality colorless diamond, we are searching for a "lack of color".

The 4Cs referred to in this quality assessment are as follows:


Arguably the most important factor in determining the quality of a diamond—cut.

When discussing the cut of a stone we are not simply referencing the shape of the diamond, oh now, there is far more to it than that!

We are talking about the symmetry and balance of the diamond’s facets, whether they are smooth and allow light to easily pass through, and whether they all uniformly meet together at a single point.

We’re looking for symmetry and balance.

The cut is where true craftsmanship comes into play.

A well-cut diamond optimizes the stone for maximum fire, brilliance, and scintillation. It is what brings the diamond to life!🌟


Where colorless diamonds are concerned we are looking at the "absence" of color as opposed to the "presence" of color. The more clear and color-free a diamond rates on the color grading chart, the more valuable we deem it to be.

On the color grading chart the categories are split into groups;

  • Colorless (D-F)
  • Near Colorless (G-J)
  • Faint (K-M)
  • Very Light (N-R)
  • Light (S-Z)

Colorless diamonds (D-F) are the rarest and highest valued diamonds that most would love to get their hands on! However, the second category of colorless (G-J) is what is considered colorless to the naked eye.

With their lower price tag but near-colorless look (as far as the eye is concerned), they make for a great option when that upper category is just out of reach!


Clarity refers to the unique marks that can be found within or on the outside of the diamond.

As they are formed beneath the Earth’s crust under immense heat and pressure, it isn’t unusual for them to emerge with small flaws known as blemishes or inclusions or, my personal favorite, birthmarks.

Of course, the fewer flaws a diamond has the more valuable they become as their brilliance and shine are not obstructed by the dark markings.

There are six categories for grading the clarity of a diamond:

  • Flawless (FL)
  • Internally Flawless (IF)
  • Very, Very Slightly Included (VVS1 and VVS2)
  • Very Slightly Included (VS1 and VS2)
  • Slightly Included (SI1 and SI2)
  • Included (I1, I2, and I3)

Where diamonds are concerned the fewer inclusions and blemishes, the better!


Both a diamond and a gemstone are weighed using metric carats. Now, this is different from the karat of an 18kt gold ring which measures gold purity.

One carat is equal to approximately 0.2 grams of weight. To put it into perspective, that’s roughly the same weight as a paper clip!

A larger stone will indeed increase the value of the diamond but the culmination of all other factors involved will be what decides on the overall quality. For example, two diamonds of the same carat weight can be priced very differently depending on the color, cut, and clarity.

Does the 4Cs system apply to colored gemstone grading?

The short answer? 👉🏻Yes… and no.

The 4Cs are prioritized differently and adapted to the criteria for assessing colored gemstones (including colored diamonds).

When purchasing a colorless diamond, what we’re really after is a pure stone that shines bright with white light. It is this white light of a colorless diamond that allows it to shimmer, reflecting light between its facets and back into the eye of the beholder.

This is quite different in the case of colored gemstones.

4Cs and Colored Gemstone Quality Assessment: Pink Sapphire

When searching for a colored stone we pay particular attention to exactly that—its color.💡 The intensity, even tone, and shade of color is the dominant factor in evaluating the quality of a colored gem.

For every stone, the cut quality will always be considered of high importance. Quality craftsmanship in the case of a colorless diamond will allow it to glisten and exude brilliance and fire. Where colored gemstones are concerned, the cut quality will have a direct impact on the stone’s symmetry and light reflection which in turn will enhance or dull the vibrancy of color.

For colored gemstones, color rules all.

Color is KING.

How to assess the quality of colored gems?

Below we are going to break down how to assess the quality of colored fancy diamonds and other colored gems.

Whilst there are similarities and overlaps using the 4Cs grading system for both, there are some notable differences between the two that are worth exploring.

Let’s dive in!

Part I: Assessment for fancy colored diamonds

Before we get started, let’s take a look at some pretty impressive fun facts that can be found on these plush fancy colored diamonds according to the GIA;

  • Only one in every 10,000 diamonds mined has a fancy color. Talk about rare!
  • The most expensive gem ever to be auctioned was called the Pink Star Diamond. At 59.60 carats it sold for a whopping $71.2 Million!
  • The Hope Diamond is a greyish blue "Fancy Deep" colored diamond. At 45.52 carats it is considered the world’s most famous gem.

The GIA intensity grading scale

The GIA has got us covered. The intensity grading scale was designed to enable us to categorize the color intensity of colored diamonds in order to gauge their quality.

The nine intensity grades are as follows;

  • Faint
  • Very Light
  • Light
  • Fancy Light
  • Fancy
  • Fancy Intense
  • Fancy Vivid
  • Fancy Deep
  • Fancy Dark

Below is a chart to explain how these categories differ from one another. As a rule of thumb, the more vibrant and strong the shade of color, the more intense it is deemed to be and therefore the more valuable it is considered.

Fancy Color Diamond Color Intensity Chart
Image: Leibish

The chart shows very clearly the array of colors ranging from soft light tones to deeper richer colors on the right-hand side of the scale.

Rarity equals quality. The rarer the colored diamond the greater the price we can demand for it.

Saturated pinks, blues, and greens are the rarest and therefore most valuable fancy colored diamonds!

The 4Cs of assessing fancy colored diamonds

Color: Richness and intensity of color are the most important factors when purchasing a fancy colored diamond. As always, rarity equates to value when it comes to stones of all kinds and colored diamonds are rare indeed.

A beautiful depth of color and tone in a fancy colored diamond will always be of high value.💰

Carat: Let’s keep talking rarity, shall we? Second to the color of a fancy-colored diamond, carat weight will have a pretty hefty impact on its final price. Large colorless stones are rare to find, but large colored diamonds are even more so.

Because of this, even a small increase in carat weight will have a dramatic effect on the value of a colored stone.

Clarity: Believe it or not, clarity is not something we need to overly concern ourselves with when it comes to colored diamonds.

In a colorless diamond, inclusions may appear obvious and intrusive to the eye however, the color of a colored diamond can easily disguise these inclusions. Regardless, inclusions can be overlooked when a stone’s color is considered intense and luxurious.

Cut: In contrast to colorless diamonds which utilize the cut of the stone to enhance brilliance and fire, the cut of a colored diamond is maximized to enhance the overall hue and tone. It plays a supporting role in taking the already stunning colored stone and refining it in order to optimize the depth of color.

Natural Fancy Color Diamonds vs. Treated Color Diamonds!
Be careful when on the lookout for your next fancy color diamond as there are treated color diamond options out there but they may not be what you want!

Treated colored diamonds often take the cheapest of natural fancy diamonds, often the brown-colored diamonds, and chemically enhance them with high pressure and high temperature to give the illusion of a natural fancy colored diamond.

Many people consider these to look false due to the extreme intensity of the stone’s color which makes them look more akin to a semi-precious gemstone.

The price is low for a reason where treated colored diamonds are concerned, they are made from the cheapest of natural diamonds!

Part II: Assessment for other colored gems (Non-diamonds)

Now let’s take a look at other non-diamond colored gems. Perhaps the biggest difference between the colored diamonds and non-diamond colored gems we are about to discuss, is that there is a great deal more subjectivity.

Indeed, your own personality and aesthetic preferences will play a rather big part in how a non-diamond-colored gem moves you.😎

Gemologist Inspecting a Colored Gem and Assessing Its Quality

Whilst the  4Cs play their part, much like the colored diamond (and colorless diamonds) above, there are also other components to consider here.


There are three factors involved in evaluating color in colored gemstone;

  1. Hue (red, green, blue, etc)
  2. Saturation (depth and richness of the color)
  3. Tone (lightness and darkness)

All three of these elements are taken into consideration when evaluating the quality of color. However, whereas a fancy colored diamond will always be considered of higher value with greater intensity, that is not always the case for other colored gemstones.

Indeed a richness in hue and saturation may be desirable however there are many cases where softer, lighter-colored stones are incredibly sought after.

For example, a blue-green tourmaline gemstone from Afghanistan or Pakistan will sell for a much higher price than their more saturated cousins due to greater desirability.

Color Distribution

Also known as "uniformity of color", color distribution describes the evenness in color across the entire stone.

With color being the number one ranking factor in a colored gems quality assessment, it makes sense that we’d like it to be even, right?

Color zoning is the term used when talking about uneven color distribution in a gemstone. What we want is no eye-visible face-up zoning. This means, when looking at a stone with our naked eye, we don’t want to see any darker areas or splotches of color.

A stone that has what is considered "heavy zoning" will have very clear lighter and darker areas across the surface of the stone…and we don’t want that!


Does the country of origin truly matter? In some cases, very much so!

A specific gem that has been mined and uncovered from a specific location can oftentimes increase the value of the stone by up to 15%. So, yes, it can matter.

To put it in perspective, an intense blue sapphire from Kashmir will command a far higher price than one that is mined anywhere else in the world.

Location, location, location!

The GIA has what is known as the GIA Colored Stone Identification and Origin Report which does its best to discover the country of origin for every stone. Unfortunately, this cannot always be the case.

The problem here is that it is difficult to obtain an accurate origin report as there are only a few major grading labs that have the necessary equipment to do so.

It requires unique spectroscopic data and chemical samples to help identify the true source of the stone by matching its data to the references of gemstones whose origins we already have samples of.

Sapphire, red spinel, ruby, emerald, and paraiba tourmaline are all colored stones that qualify for this report. Yet, it does not always guarantee results. If the data samples collected overlap and identify with gems for two or more locations, they are only able to classify the location as unidentified.

Clarity Scaling System

The clarity scale for grading colorless diamonds simply does not apply to colored gemstones.

It’s difficult to put these little gems into a clearly defined box in this instance as there are many circumstances where the presence of inclusions is considered of great benefit.😮

They can enhance and alter the color perception for the better and can provide reassurance of the stone’s natural origins.

The GIA (Gemological Institute of America) created three different categories in order to classify these colored stones; Type 1, Type2, and Type 3.

Type 1 Gemstones

Type 1 Gemstones include beryl gems such as; aquamarine, blue zircon, tanzanite, smoky quartz, citrine, pale-colored amethyst, yellow and green chrysoberyl, and spodumene.

Type 1 Gemstones are usually what we can consider as "eye clean" meaning that there are no visible inclusions when looking with the naked eye.

Type 2 Gemstones

Type 2 Gemstones include amethyst, garnet, peridot, spinel, ametrine, andalusite, alexandrite, corundum (ruby and sapphires), tourmaline that is not green, pink or watermelon, and zircon that is not blue.

These gems are often included although some can be found and considered eye-clean. Minor visible inclusions mean that these are still often used for jewelry purposes

Type 3 Gemstones

Type 3 Gemstones include green emerald, varieties of tourmaline, and red beryl.

These stones almost always feature heavier inclusions and rarely rate higher than an IF in clarity rating.

As you can see, it’s certainly not as clear-cut as colorless diamonds!

Carat and Size

Bigger always means better, right?

Non-diamond colored gemstones use the same carat metric system to weigh each stone as is used for colorless diamonds. Whilst a larger stone is far rarer and more desirable, the criteria for determining its value are slightly more complex than that.🤔

Heart-Shaped Blue Sapphire Pendant Necklace

A large colored stone that has a rich intensity (saturation) and an even tone can be taken to a master cutter and carved into a piece fit for royalty. If a stone such as this also happens to be uncovered in one of the highly sought-after locations that we spoke of earlier, then many gemstone lovers will happily pay a high price for such a specimen.

However, stones of this size and this quality are hard to come by.

Oftentimes these larger stones incur far more inclusions and suffer from color zoning which diminishes their potential.

As well as this, there is only so big a stone can be for us to wear it on our hands or around our necks! Therefore, once a stone goes beyond a certain size that is most common in jewelry the demand for them decreases.

So, whilst bigger generally means better, it is simply not always the case.

In contrast, some stones are naturally larger in size which means that when these saturated stones are smaller they can come in at a much higher price than might be expected.

Kunzite and Aquamarine are great examples of this.


The shape is not the same as the cut, as any cutter will tell you.

The shape concerns the final outline of a gem once it has been through the cutting process. Different shapes might include round, princess cut, pear, emerald cut, etc.

Whilst the quality of the cut is far more important than the shape itself, there are certain shapes that are not often used with certain colors, and vice versa. Tourmaline, for example, will rarely be found cut into a round shape.

As styles and fashions change so do our preferences for colored stones. Pear-shaped colored stones are not often sold as anything other than earrings or pendants which limit their positioning in the market.

Certain shapes have more appeal because they suit current trends and designs. These trends will always determine how to best utilize these rough stones in order to create a highly sale-able piece of jewelry.📈

With regards to quality, however, the shape is low on the list of priorities compared to...

Cutting Quality

💡For colored stones COLOR IS KING.

And for this reason, cut quality is incredibly important. Master craftsmanship is required to take a rough colored stone and carve it into a stunning gem.

Much like the fancy colored diamonds, the cut will have a direct effect on the final quality of a stone; impacting hue, saturation, and tone. It is the job of the cutter to take a good hard look at the rough stone in front of them and decide which size and shape would yield the best results with the stone at hand.

For example, a stone that is deeply saturated may well lose value if cut into a larger stone as it may appear too dark.

Every rough stone is carefully considered. The pros and cons are weighed and the cutter will decide how best to proceed to make the most out of it. Sometimes this will involve cutting it down to one larger piece or they may decide to cut a multitude of stones from this one rough gem.

The White Paper Test
To best determine how to utilize the rough stone for best results, a cutter may use what is called "The White Paper Test".

I know, exotic!

This technique is often used when working with particularly dark stones to help uncover the evenness of color tone. The rough stone is placed on a white piece of paper under incandescent and then fluorescent light.

The cutter is looking to see how much light is reflected through the stone from the white paper below to determine the true depth of color. If the stone is too dark then they will consider cutting it into smaller gems where they will hold more value.

General buying assessment

The factors mentioned below are usually offered by jewelers to help customers filter and find the gems that best suit them:

  1. Color (Hue)
  2. Shape
  3. Carat or Size
  4. Origin
Colored Gem General Buying Assessment With Filtering Options
Buying green emerald (James Allen)

Then, if provided, customers can learn more about their chosen gemstone through the colored stone identification report or certificate if one has been provided.

Assessing colored gemstones is more subjective

Unlike colored diamonds which still have a far clearer and definitive method for determining quality and desirability, colored gemstones are far more subjective.

👩🏻‍🏫Inclusions and markings can be hidden (and forgiven) for a stone that is of the perfect hue, tone, and saturation. This will be different for everyone. A combination of the three color components along with the shape and cut of a colored gemstone is going to be of individual preference.

Some people love the pale, softer colors whilst others like a deep and dark intensity in their colored stone.

Where these gems are concerned, there are guidelines to help us understand the stone we have in front of us but ultimately, it will come down to personal preference.

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Our advice for average buyers about assessing the quality of colored stones

It’s very clear that trying to justify the quality of a colored gemstone is a pretty complex process.

There are many aspects that cannot be clearly categorized the way a colorless diamond can and so when it comes to buying, we have to reply a little bit more on gut instinct.

📝Take the following into account when purchasing a colored gemstone:

  • Assessing the quality of a colored gemstone is far more subjective. That’s right, you’re going to have to rely on instinct a lot more where these stones are concerned. It is difficult to uncover common industry standards across the varying contributing factors involved. This makes true quality assessment far less definitive. For example, where inclusions clearly lessen the value of a colorless diamond, they can sometimes enhance the beauty and value of a colored stone.
  • The quality of a colored gemstone is, well, almost irrelevant! If the industry decided tomorrow that the palest shade was actually considered the highest quality, would that stop you from favoring the darker tones? Colored gems are a great way to express personality! So when buying a colored gemstone, the quality assessment isn’t necessarily a top priority.
  • Always buy from a reputable jeweler to avoid scams! Unfortunately, to the untrained eye, it can be hard to distinguish between high-quality colored stones and cheaper gemstones. Some jewelers (without the reputation to uphold) may try to sell you a stone for a higher price when in fact, it’s not the real deal!
  • Always try to have a close look at the stone before you buy! This is an emotive process everybody! When subjectivity plays such a big role, you owe it to yourselves to look at it and even touch it before you hand over your cash!
  • If the above can’t be done, then head over to a reputable jeweler such as James Allen and Brilliant Earth to view a high-resolution 360-degree image of their stones. It’s pretty cool!

How do we really assess the quality of a colored gem?

With colored gemstones, it really is all about personal taste.

Although we can look at the 4Cs along with the origin and other factors, ultimately it all comes down to your own personal preferences. What is aesthetically pleasing to you?

The most important thing to remember is that COLOR IS KING.

Color is the main determining factor in the quality of a colored stone according to vague guidelines. However, even with these guidelines in place, how you feel and what you want is what should drive you when on the lookout for that next colored gem.

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