Diamond: a complete guide to grading and price

Introduction

This article is intended for future diamond buyers, investors, jewelry enthusiasts, and everyone interested in gemstones. Here, we will discuss what a diamond is, how it is valued, what determines its price, the various diamond colors, how certifications (GIA, CIBJO, IGI) work, and why all this information is crucial for making an informed decision when choosing a diamond. The article will explain key terms and provide information for both beginners and advanced readers.

You will learn what a diamond is, how its value and price are determined, which factors cause price differences, how to recognize different types of diamonds, what the main certificates are, and why they are important. This will help you avoid mistakes and choose the most suitable diamond according to your needs.

What is a diamond?

A diamond is a miracle of nature – a crystallized carbon mineral formed over millions of years. Diamonds are extremely hard stones, which is why they are used not only in jewelry but also in industry. It is one of the most valuable gemstones in the world, famous for its brilliance, hardness, and unique optical properties.

More about diamond types and properties

Further in this article, we will discuss the different types of diamonds, their colors, how they are valued, and what factors determine their price.

Why is diamond color so important?

Diamond color is one of the main factors directly determining its price. Every stone is unique, so even the slightest tint can have a significant impact on the price per carat of a diamond (a carat is a unit of weight for gemstones, equal to 0.2 grams).

What is the difference between a diamond and a brilliant?

A brilliant is a diamond that has been specifically cut into a round brilliant shape. This cut gives the stone the maximum sparkle and charm.

• Diamond – a natural gemstone composed of carbon.
• Brilliant – a round-cut diamond characterized by exceptional brilliance.

It is this specific shape that gives the stone the greatest sparkle. Therefore, the price of a 1ct brilliant is often higher than that of a raw diamond of the same weight.

Brilliants are popular for their sparkle and are often chosen for investment or jewelry. The value of brilliants depends on the cut quality, color, and clarity, making these factors extremely important when choosing a brilliant.

How is a diamond’s price determined?

The price of a diamond depends on several key factors, known in the international market as the “four Cs” (4Cs):

• Color: the more colorless the diamond, the more valuable it is.
• Clarity: the fewer inclusions or defects, the higher the value.
• Carat: the weight of the diamond, measured in carats (1 carat = 0.2 g).
• Cut: the quality of the cut determines the sparkle and appearance.
• Certificate: international certificates (e.g., GIA, IGI, CIBJO) confirm the diamond’s authenticity and characteristics.

These factors are evaluated in professional laboratories, and their combination determines the final market price of the diamond.

Colorless diamonds

Colorless diamonds are considered the most valuable. The less tint a stone has, the more expensive and rare it is. Such stones are most commonly used in wedding and engagement rings.

More about the color scale

Next, we will discuss how diamond color is evaluated according to international scale systems and what the main differences are.

Diamond color scale according to GIA

Colors are evaluated in alphabetical order from D (colorless) to Z (light yellow or brownish tint). The more colorless the stone, the rarer and more valuable it is.

What are GIA, CIBJO, IGI and why are their certificates important?

• GIA (Gemological Institute of America) – one of the world’s most famous and reliable gemological laboratories, which creates international diamond grading standards and issues certificates.
• CIBJO (The World Jewellery Confederation) – an international jewelry organization whose standards are also used by the Lithuanian Assay Office.
• IGI (International Gemological Institute) – another international laboratory that grades diamonds and issues certificates.

Certificates from these institutions are important because they guarantee the diamond’s authenticity, provide an accurate description of its properties, and help the buyer make an informed decision.

GIA color grade and comparison with CIBJO (used in the Lithuanian Assay Office)

✅ Important to know:

• GIA uses a letter scale (D–Z).
• CIBJO uses terms (EW, RW, W, STW, TW).
• The differences often confuse buyers, but in reality, these are just different systems.

More about color’s impact on price

Next, we will discuss how a diamond’s color determines its price and why it’s important to choose certified stones.

How does color determine diamond price?

The price of a diamond depends on its color grade. For example, the price of a 1 carat D color diamond will be much higher than that of a J color stone of the same weight. This is one of the main reasons why it is necessary to certify stones with GIA or other laboratories.

Brilliant price according to color

The price of a 1ct brilliant can differ by several thousand euros due to color alone. The price of brilliants depends not only on color but also on cut quality, clarity, and other characteristics. Colorless stones (D–F) are the most expensive, while those with a softer tint (H–J) are more popular due to a better price-to-quality ratio.

More about fancy color diamonds

Next, we will discuss what makes fancy color diamonds special, how they are valued, and what their main types are.

Fancy color diamonds

In addition to classic colorless diamonds, there are also fancy color diamonds. They can be natural or modified (where the color is changed through technological methods).

Fancy color diamonds – uniqueness and exceptional value

What determines color and intensity?

Fancy color diamonds differ in their beauty from classic colorless stones. Their color is determined by chemical impurities or changes in the crystal structure. For example, nitrogen atoms provide a yellow or orange color, boron provides blue, and natural radiation provides green.

An important criterion is color intensity. The more saturated and vivid the color, the more expensive the diamond. Intensity is divided into several levels – from “faint” (barely noticeable color) to “vivid” (very bright).

Another aspect is overtone, or secondary tint. For example, a pink diamond may have a purple or orange overtone, which makes it more unique.

Main types of fancy color diamonds

Yellow diamonds

Yellow diamonds are among the most popular colored stones. Their color is caused by nitrogen impurities, and deep yellow diamonds are also called “canary yellow.”

• Where are they found? Mostly in South Africa.
• Value: Light yellow diamonds are cheaper, while bright “fancy vivid” ones are very expensive.
• Interesting fact: One of the world’s most famous is the “Tiffany Yellow Diamond.”

Brown diamonds

Brown or “champagne” diamonds feature warm tones – from light brownish to dark chocolate.

• Where are they found? Mostly in the Argyle mine in Australia.
• Value: Brown diamonds are more affordable in terms of price.
• Interesting fact: Collectors love them for their warm, natural tint.

Pink diamonds

Pink diamonds are considered some of the most romantic and rarest.

• Where are they found? In the Argyle mine in Australia (closed in 2020).
• Value: Their value is constantly rising due to limited supply.
• Color scale: From soft pink to deep purple.
• Interesting fact: At auctions, pink diamonds are often sold for record prices.

Blue diamonds

Blue diamonds are famous for their exceptional beauty and luxury.

• Where are they found? In South Africa, India.
• What gives the color: Boron impurities.
• Example: The famous “Hope Diamond.”
• Value: Some of the most expensive on the market.

Green diamonds

Green diamonds stand out due to their unusual origin.

• What gives the color: Natural radiation acting over millions of years.
• Where are they found? In Central Africa, South America.
• Tones: From light mossy to deep dark green.
• Interesting fact: Very rare, therefore especially valuable.

Orange diamonds

Warm, glowing orange diamonds are considered highly charismatic.

• What determines the color: A special arrangement of nitrogen atoms in the crystal lattice.
• Rarity: Purely orange ones without a red or brown tint are very rare.

Red diamonds

Red diamonds are the rarest in the world.

• Reason for color: A special deformation of the crystal structure.
• Where are they found? Mostly in Australia.
• Value: Their price often exceeds even the value of pink or blue diamonds.
• Interesting fact: At auctions, red diamonds reach astronomical sums.

Other tints

In addition to the primary colors, many other tints exist:

• Black diamonds – usually with graphite inclusions, popular in modern jewelry.
• Purple and violet – very rare, often having a blue or pink overtone.
• Grey – elegant, often called “salt & pepper” due to inclusions.
• Champagne and cognac – warm tones, popular for everyday style.
• Salt & pepper – diamonds with many inclusions that give a unique, cosmic effect.

✅ Important to know:
Fancy color diamonds can be natural or modified. Natural ones are formed in nature, while modified ones have had their color changed artificially, for example, by heating or irradiation. Natural fancy color diamonds are always significantly more expensive and more valuable as an investment.

Fluorescence in diamonds and its impact on color and price

What is fluorescence?

Fluorescence is a diamond’s property to glow with blue, or more rarely yellow or orange light, in an ultraviolet environment. Approximately 25–30% of all diamonds exhibit fluorescence of varying strength. Although it is usually invisible to the naked eye, strong fluorescence can visually change the stone’s color. For example, diamonds with a yellowish tint can appear whiter due to fluorescence, improving their appearance. However, very strong fluorescence sometimes gives the stone a “milky” or cloudy effect, reducing transparency.

How does fluorescence affect the price?

• For colorless high-quality diamonds (D–F colors), strong fluorescence usually decreases the value, as such stones are valued for their crystal clarity and pure color.
• For G–J color diamonds, fluorescence can be beneficial as it helps them appear cleaner and whiter.
• In the market, fluorescence can either increase or decrease a diamond’s price – it depends on the balance of color, clarity, and overall quality.

Fluorescence in diamonds according to GIA grading

In a GIA certificate, fluorescence is always indicated as it is one of the additional diamond quality criteria. The evaluation is provided in five levels:

• None: The diamond does not glow at all under UV light. This is usually considered the safest choice, especially for investment diamonds.
• Faint: Barely noticeable fluorescence that has no impact on the diamond’s appearance or price.
• Medium: Easily noticeable, can improve slightly yellowish diamonds by giving them a whiter appearance.
• Strong: Obvious fluorescence, which can have both a positive effect (when masking yellowness) and a negative effect (when creating milky cloudiness).
• Very Strong: Highly visible, usually decreases the diamond’s value as it can negatively affect transparency and brilliance.

✅ Important to know:
In GIA reports, fluorescence is always described objectively, but its final impact depends on the stone’s color, clarity, and individual aesthetic preferences. Some collectors even prefer strongly fluorescent diamonds for their uniqueness.

Lab-grown diamonds and color

Lab-grown diamonds can be both colorless and fancy colored. Their color depends on the growth process and the technologies used. This allows the market to offer colored stones at an affordable price.

Diamond colors and investment

Investment diamonds are most commonly chosen from the colorless (D–F) category. When investing in diamonds, it is important to consider their quality, authenticity, certificates, and market demand, as these factors determine their investment value. Such stones retain the most value. However, some rare colors, such as red or blue, are already considered extremely valuable for investment.

Diamond color by clarity and shape

Color is not the only criterion – it is closely related to clarity, shape, and cut quality. For example, oval-shaped diamonds can appear lighter than round ones of the same clarity and color.

Evaluation by the Lithuanian Assay Office

The Lithuanian Assay Office also evaluates diamond color according to CIBJO standards. This ensures that the stone meets international requirements and is certified.

GIA certificate

A GIA certificate confirms the diamond’s color, clarity, carats, and cut. It is an official document that ensures your diamond is real.

Which to choose: GIA or the Lithuanian Assay Office?

Both systems are reliable, but a GIA certificate is international, while the Lithuanian Assay Office is a mandatory confirmation in Lithuania.

Diamond color and carats

It is important to know that the price of a 1-carat diamond depends heavily on the color. For example, a G color stone will be cheaper than a D color stone, even though both weigh the same.

How does color change by size?

Large diamonds reveal their color more. Therefore, a 2 ct brilliant with H color will appear yellower than a 0.5 ct one with the same color grade.

Are fancy color diamonds suitable for everyday wear?

Yes, fancy color diamonds can be worn daily. However, their choice depends on style – for example, pink or blue stones are more often chosen for special occasions.

Modified fancy color diamonds

These are stones whose color has been changed using special methods – heating or radiation. They are cheaper than natural fancy color diamonds.

How to distinguish a natural fancy color diamond?

A certificate is the only reliable way. GIA or IGI will indicate whether the color is natural or treated.

Diamond color and light

Diamond color depends on lighting – it appears most accurately in daylight. Therefore, it is recommended to view stones in natural light.

Diamond colors and psychology

Each color has its own symbolism. Pink diamonds are associated with love, blue with loyalty, and green with nature and renewal.

Diamond color and fashion

In recent years, non-traditional colors have become increasingly popular. Black diamonds and lab-grown colored stones are becoming part of modern jewelry.

We also offer diamonds of various colors in our assortment, reflecting contemporary jewelry trends.

Diamond authenticity

Diamond authenticity is one of the most important aspects to consider when choosing this gemstone. Diamonds are rare and valuable, so their authenticity is checked using gemological knowledge and special devices. Every diamond has unique properties – color, clarity, shape, and weight – which can be used to determine its authenticity. Certified diamonds are valued much higher than those without a reliable certificate. A GIA certificate is one of the most reliable documents confirming that a diamond is real and matches the specified characteristics. Therefore, when choosing diamonds, it is always worth choosing those that are certified, as only then can you be sure of their origin and value.

What should you choose?

If investment is your main priority, choose a colorless diamond with a GIA certificate. If you want uniqueness, fancy color stones will be a perfect choice.

Conclusion

Diamond color is one of the most important criteria determining its price, value, and beauty. From the D to Z scale, from colorless to colored stones – every diamond is unique and worthy of attention.