Diamond Cut
Cut is about more than a diamond’s shape. It decides how well the stone catches light and sends it back to your eye, and that is where its sparkle comes from. A well-cut diamond looks bright, lively and full of fire. A poorly cut one can look flat and dark, even if its colour and clarity grades are high.
A great cut can also make a diamond look bigger. Because light is reflected so efficiently, a well-cut stone appears larger than a poorly cut stone of the same carat weight. Ideal cuts have strong brilliance and a wider face than deeper-cut diamonds.
Of the 4Cs, cut is usually seen as the most important, since it has the biggest effect on how a diamond looks overall. This is why jewellers advise buyers to look at the cut first.
Types of Diamond Cuts
A diamond’s proportions and symmetry define the quality of its cut, and only a skilled craftsman can create a high-quality one. Cut grades run from Ideal to Poor, and even an untrained eye can see that higher grades sparkle more.
- Ideal: Outstanding sparkle and flawless symmetry, cut to perfect proportions for refracting light.
- Excellent: Exceptional sparkle with even patterns.
- Very Good: Great sparkle and polish, with good symmetry.
- Good: Fine sparkle, with reasonable polish and symmetry.
- Fair: Low sparkle and polish, and not always symmetrical.
- Poor: Dim and asymmetrical, with uneven spots on the surface.
The Diamond Color Scale
Diamond colour is graded from D to Z, and the grades fall into five categories. The closer a diamond is to colourless, the whiter it looks.
The 5 Color Categories
- Colorless
- Near Colorless
- Faint
- Very Light
- Light
A colorless diamond is almost pure white, while lower grades have a yellowish tint caused by trace nitrogen.
Color differences are hard to spot with an untrained eye. Unless two diamonds are two grades apart, you’re unlikely to see a difference, and when the stone is face up you won’t see any color at all. Any slight tint at the side is partly hidden by the ring setting.
Diamond Clarity
Clarity measures how free a diamond is from inclusions (internal marks) and blemishes (surface flaws). The GIA scale runs from Flawless to Included, and most diamonds have tiny inclusions that don’t affect their beauty. Position matters as much as size, so it’s best to view each diamond individually.
Clarity Grades
A gemologist grades clarity under 10X magnification. The higher the number, the more inclusions are visible.
- FL (Flawless): No inclusions or blemishes. Rarest and most valuable.
- IF (Internally Flawless): No inclusions inside, only minor surface blemishes.
- VVS1 & VVS2: Inclusions very hard to see, even under magnification.
- VS1 & VS2: Small inclusions seen only under close inspection.
- SI1 & SI2: Inclusions visible under magnification, sometimes by eye.
- I1, I2 & I3: Inclusions clearly visible.
Eye-clean diamonds have no inclusions visible without magnification and are usually graded VS1 or higher.
Diamond Carats
Carat is the unit that measures a diamond’s weight, and it is one of the most objective factors in its value.
Everything You Need to Know About Carats
- What a carat is: One carat equals 200 milligrams, or 1/5 of a gram.
- Points: Each carat is divided into 100 points, so weight can be measured very precisely, to the hundredth of a carat.
- Typical sizes: Most diamonds weigh between 0.25 and 5 carats.
- Why it’s objective: Carat is a direct measure of weight, while the other Cs (cut, color and clarity) involve more judgment. Carat weight also determines how big the diamond is.
- Weight lost in cutting: Up to 2/3 of a raw diamond’s weight may be lost when it is cut and polished into a finished stone.
4 Cs of Diamonds FAQ
Which of the 4 Cs is most important in diamonds?
Cut is generally considered the most important of the 4 Cs because it has the greatest impact on a diamond's brilliance and overall appearance. However, the "most important" C is ultimately a matter of personal preference.
What is the best combination of the 4 Cs of diamonds?
There's no single "best" combination, as it depends on individual preferences and budget. However, for maximum visual appeal, many experts recommend prioritizing excellent cut, color in the G-J range, clarity in the VS1-SI1 range, and the highest carat weight your budget allows. This combination typically yields a diamond that appears colorless to the naked eye, has no visible inclusions, displays excellent brilliance, and maximizes size.
What is a diamond?
A diamond is crystallized carbon formed under extreme pressure and temperature in a lab or deep within the Earth over billions of years. It ranks as the hardest known substance and valued for its exceptional hardness (10 on the Mohs scale), brilliance, and fire.
What is a certified diamond?
Certified diamonds are diamonds certified by independent institutions such as the Gemological Institute of America (GIA), the International Gemological Institute (IGI), HRD Antwerp, and the Gem Certification & Assurance Lab (GCAL). All Brilliant Earth center diamonds are certified.
To grade a diamond, professionals use equipment to assess cut, color, clarity, and carat. They may also plot a diagram of its clarity characteristics and a graphic representation of its proportions.
How hard are diamonds?
Diamonds are the hardest known substance found on Earth. They are so hard that they rank at the highest hardness level (a 10) on the Mohs scale. Therefore, diamonds are ideal for everyday wear, making them perfect as center gems in jewelry as well as engagement rings.
How much does a diamond cost?
Diamond price varies greatly depending on rarity and quality. Diamonds with higher grades in cut, color, or clarity, or diamonds with a larger carat weight, are rarer and therefore more expensive than those with lower grades or carat weights. Lab grown diamonds are less rare than natural diamonds and are therefore less expensive.