Diamonds have fascinated people for centuries, known for their brilliance, durability and connection to life’s biggest moments. Most of us only ever see them as polished stones in jewellery, but every diamond starts out looking very different.
Understanding that journey, along with how diamonds are graded, can help you make more informed decisions when it comes time to sell.
How Diamonds Form
Diamonds are made of carbon, formed under extreme heat and pressure deep within the Earth’s mantle. Over billions of years, carbon atoms bond in a tightly packed crystal structure, creating one of the hardest natural materials known.
Volcanic activity eventually brings these diamonds closer to the surface, where they can be mined. Many natural diamonds are over a billion years old, making them one of the oldest materials you will ever hold.
What Rough Diamonds Really Look Like
In their natural state, diamonds do not resemble the finished stones seen in jewellery. Rough diamonds often look like dull, uneven stones with a slightly greasy or frosted appearance.
They may appear grey, brown or lightly tinted rather than clear, and they do not sparkle because they lack the precise facets needed to reflect light. Only a small percentage of rough diamonds are suitable for jewellery, which adds to their rarity.
The 4 Cs of Diamonds
Diamonds are graded using four main factors, often referred to as the 4 Cs. These help determine both quality and value.
Carat
Refers to the weight of the diamond. While often associated with size, how large a diamond appears can also depend on its cut.
Couper
Describes how well a diamond has been shaped and faceted. This directly impacts how light reflects within the stone and how much it sparkles.
Couleur
Measures how colourless a diamond appears. Even diamonds that look colourless can contain subtle hints of yellow or brown.
Clarté
Refers to the natural features within the diamond. Most are not visible without magnification, but they still play a role in grading. These can look like tiny specks, faint lines or cloudy areas. In many cases, they are not visible without magnification. Diamonds described as “eye-clean” appear clear to the naked eye, even if they have minor inclusions under magnification.
Carat: Understanding Weight vs Size
Carat refers to the weight of a diamond, not its physical size, although the two are often related. One carat equals 200 milligrams.
Larger diamonds are rarer, which increases their value, especially at milestone weights like 0.50, 1.00 or 2.00 carats. However, two diamonds with the same carat weight can appear quite different in size depending on how they are cut.
The Role of Cutting
Cut determines how effectively a diamond reflects light, making it one of the most important factors in its appearance.
After a diamond is mined, it is carefully shaped and polished into a finished stone. This process creates facets at precise angles, allowing light to enter, reflect internally, and return to the eye. A well-cut diamond appears bright and lively.
The way a diamond is cut can also affect how large or brilliant it appears. For example, a deep cut diamond may appear smaller than a well-cut diamond. Sometimes the diamond cutter sacrifices the quality of a cut to maintain the weight. On the other hand, a shallow cut diamond may appear larger than a well-cut diamond, but due to its lack of perfect reflection of light, it may not have the same sparkle of a well cut diamond. That is why not all the stones with the same weight, colour, and clarity have the same value.
Colour: Why Diamonds Aren’t Always Colourless
Colour measures how colourless a diamond appears. While many people expect diamonds to look icy, or clear, most natural diamonds contain subtle traces of colour. Diamonds are colour-graded by comparing them to stones of known colour under controlled lighting and precise viewing conditions.
The industry standard grading scale runs from D to Z:
- D–F: Colourless. These are the rarest and appear with no trace of colour.
- G–J: Near colourless. They still appear colourless in most settings, especially in jewellery.
- K–M: Faint colour. Slight warmth may be visible, particularly in larger stones.
- N–Z: Noticeable yellow or brown tint.
In their purest form, diamonds with a perfect carbon structure are colourless. Colour in diamonds is caused by impurities (ex. Yellow, Blue), structural defects (ex. Red, Pink), natural radiation within the Earth over billions of years (ex. Green), or large amounts of microscopic inclusions (ex. Black, White). One diamond might have a variety of these characters which result in a combination of colours such as “Bluish Green”, or “Brownish Greenish Yellow”.
Generally, because colourless diamonds are rarer than diamonds with faint or light colour, the more colourless a diamond is, the more valuable it tends to be.
When a diamond’s colour saturation goes beyond the grade Z and becomes strong enough to be clearly noticeable, it is classified as a fancy colour diamond. However, not all fancy colour diamonds are rarer than colourless diamonds. The value of a fancy colour diamond depends heavily on the specific colour it displays. For example, a colourless (D, E, F) diamond is rarer and more valuable than a fancy brown diamond with the same carat weight, cut, and clarity grades. However, a fancy pink diamond would be far rarer and significantly more valuable under those same conditions.
Clarity: The Natural Features Inside a Diamond
Clarity refers to the presence of internal features (inclusions) and surface marks (blemishes). Almost all natural diamonds contain some form of inclusions, created during their formation.
These can appear in different ways:
- Pinpoints: Tiny dots that look like specks
- Clouds: Clusters of very small inclusions that can create a hazy area
- Feathers: Fine internal fractures with a wispy appearance
- Crystals: Small minerals trapped inside the diamond
- Needles: Thin, elongated inclusions
Diamonds are graded under 10x magnification, which means many inclusions are not visible to the naked eye.
Clarity grades range from Flawless (FL), where no inclusions are visible under magnification, to Included (I1–I3), where inclusions may be visible without magnification and can affect appearance or durability.
Between these are common grades such as:
- VVS (Very Very Slightly Included): Extremely difficult to see inclusions
- VS (Very Slightly Included): Minor inclusions, typically not visible to the eye
- SI (Slightly Included): May be visible under magnification, sometimes visible by naked eye in larger stones
A term often used in practice is eye-clean, meaning the diamond appears clear without magnification, even if inclusions are present. Larger inclusions or dense clouds can reduce sparkle or create a slightly dull or milky appearance.
Diamond Treatments: Colour and Clarity Enhancements
Some diamonds undergo treatments to improve their appearance, particularly their colour or clarity. These treatments can make a diamond appear cleaner or more visually appealing than it originally was.
Common diamond treatments include:
- Laser drilling
- Fracture filling
- High pressure, high temperature treatment (HPHT)
- Irradiation
- Coating treatments
Some treatments are permanent, while others can be affected by heat, repairs or everyday wear over time. Because treated diamonds differ from natural untreated stones, they are typically valued differently within the secondary market.
Professional testing is often required to identify certain treatments, especially since enhancements may not be visible to the naked eye.
Selling Your Diamond: What to Expect
When it comes time to sell, diamonds are evaluated based on all of these factors together, not just size or appearance at first glance.
At Canada Gold, each diamond is assessed individually by trained professionals. We consider the 4 Cs, along with condition, craftsmanship and current market demand, to provide a fair and competitive offer.
We purchase a wide range of diamond jewellery, including engagement rings, earrings, bracelets and loose stones. Some coloured gemstones may also be considered on a case by case basis.
We do not purchase raw or uncut diamonds, treated/enhanced stones or lab-created diamonds. Our focus is on natural diamonds that can be resold within the secondary market.
Whether your diamond is a smaller accent stone or a larger centrepiece, our team provides a straightforward process, clear explanations and a no obligation quote. If you choose to proceed, payment is immediate, making it easy to move forward with confidence.
