When people talk about how beautiful a diamond is, they often mention its size or shape. But the real secret behind a diamond’s sparkle is something less obvious: the cut.
Diamond cut is not about whether a diamond is round, oval, or pear-shaped. Instead, it refers to how well the diamond has been cut and proportioned to interact with light. A well-cut diamond can look brighter and more lively than a larger diamond with a poor cut.
In this guide, we’ll explain diamond cut simply — what it means, why it matters so much, and what actually makes a diamond sparkle.
What Does “Diamond Cut” Really Mean?
Diamond cut describes how precisely a diamond’s facets have been shaped, angled, and polished.
A well-cut diamond allows light to:
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Enter through the top
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Reflect internally from facet to facet
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Return to the eye as sparkle and brilliance
If the cut is too shallow or too deep, light escapes through the sides or bottom of the diamond — and the stone appears dull, even if it’s high quality in other ways.
In short:
Cut determines how much life and sparkle the piece of diamond jewellery has.
Diamond Cut vs Diamond Shape: What’s the Difference?
This is one of the most common points of confusion.
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Diamond shape is the outline of the stone (round, oval, cushion, pear, princess, etc.)
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Diamond cut is the quality of the proportions, symmetry, and polish
For example:
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A round diamond can be beautifully cut or poorly cut
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Two diamonds of the same shape and size can look completely different depending on cut quality
Cut is about performance, not appearance alone.
Why Diamond Cut Is So Important
Of the traditional “Four Cs” (Cut, Colour, Clarity, Carat), cut has the biggest impact on how a diamond looks.
A well-cut diamond:
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Sparkles more
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Looks brighter and more lively
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Often appears larger than its carat weight
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Has better overall balance and durability
Even though diamonds are extremely hard, a poorly cut stone can have weak points that make it more vulnerable to chipping, especially around thin edges.
What Actually Creates Sparkle?
Sparkle isn’t just one thing — it’s a combination of how light behaves inside the diamond.
A well-cut diamond produces:
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Brilliance – bright white light reflections
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Fire – flashes of rainbow colour
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Scintillation – the sparkle you see when the diamond moves
All three depend on precise cutting and symmetry. This is why cut quality matters more than many people realise.
Common Diamond Cuts You’ll See in Jewellery
More than 70% of diamonds are cut as round brilliant diamonds, as this cut is designed to maximise sparkle.
Other popular cuts (often called “fancy cuts”) include:
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Princess (square)
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Cushion
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Oval
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Pear
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Marquise
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Emerald
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Asscher
Each cut has its own personality and style, but within every shape, cut quality still determines how lively the diamond looks.
How Are Diamonds Cut?
Diamond cutting is a highly skilled process that combines mathematics, experience, and craftsmanship.
Very simply, the process involves:
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Planning the diamond to make the best use of the rough stone
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Shaping the diamond into its basic form
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Cutting and polishing the facets to exact angles
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Inspecting and grading the finished diamond
The goal is always the same: to maximise beauty while preserving as much weight as possible.
Choosing a Well-Cut Diamond
When choosing diamond jewellery, prioritising cut quality is one of the best decisions you can make.
A slightly smaller diamond with an excellent cut will usually look:
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Brighter
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More eye-catching
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More elegant
than a larger diamond with a poor cut.
If you’re unsure where to compromise, cut is rarely the place to do it.
In Summary
Diamond cut is what brings a diamond to life.
While shape, size, colour, and clarity all matter, cut is what determines sparkle, brilliance, and overall beauty. A well-cut diamond reflects light beautifully, looks more vibrant, and often appears larger and more valuable.
Understanding diamond cut doesn’t require technical knowledge — just knowing that how a diamond is cut matters more than many people expect.
If you’re choosing diamond jewellery, focusing on cut quality will help ensure your diamond shines for years to come.
Frequently Asked Questions About Diamond Cut
What is diamond cut?
Diamond cut refers to how well a diamond’s facets have been shaped, angled, and polished. It affects how light reflects inside the stone and has the biggest impact on sparkle.
Is diamond cut more important than carat size?
Yes. A well-cut diamond often looks brighter and larger than a bigger diamond with a poor cut.
What is the best cut for sparkle?
Round brilliant cut diamonds are designed to maximise sparkle, but any shape can be beautiful if it is well cut.
Is diamond cut the same as diamond shape?
No. Shape describes the outline of the diamond (round, oval, pear), while cut describes the quality of how the diamond has been crafted.
How can I tell if a diamond is well cut?
Look for grading terms such as Excellent or Very Good, and observe how lively and bright the diamond appears in natural light.
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