How To Choose A Diamond?

Introduction

For centuries, diamonds have been admired as the ultimate symbol of love, strength, and timeless beauty. Each stone tells a story -of immense geological pressure, of human craftsmanship, and of the emotions we attach to it. At Sara Peymanpour London, we believe that understanding the qualities of a diamond not only helps you make an informed choice, but also deepens your appreciation of its rarity and radiance.

The 4Cs of Diamonds

Choosing a diamond begins with understanding what makes each stone unique. No two diamonds are exactly alike, and their beauty and value are defined by a universal grading system known as the 4Cs -cut, colour, clarity, and carat weight. These four characteristics determine how a diamond looks, how it performs in light, and ultimately, how it is priced. Explore the 4Cs below to discover what each means, and how to select the perfect diamond for you.

Colour - From Colourless to Warmth

Diamond colour measures how close to colourless a stone is, graded on a scale from D (completely colourless) to Z (noticeable yellow or brown). The less colour present, the rarer and more valuable the diamond. That said, certain settings -such as yellow or rose gold- can beautifully complement warmer-toned diamonds, making colour a flexible factor that can be matched to personal preference and design.

Click on the GIA slider above to compare diamond colour grades from D to Z.

Click on the GIA slider above to compare diamond clarity grades from FL to I3.

Clarity - Nature’s Fingerprint

Clarity evaluates the presence of natural characteristics called inclusions (internal) and blemishes (external), which form as the diamond develops. Grading ranges from Flawless (FL) to Included (I). Most inclusions are microscopic and invisible without magnification, meaning they rarely affect the overall beauty of the diamond. Still, larger or poorly placed inclusions can influence appearance. Reviewing a diamond’s clarity report will show its unique internal features, its natural fingerprint.

Cut - The Spark of Life

The cut of a diamond refers to how well its proportions, symmetry, and polish interact with light. It is the factor that determines brilliance (white sparkle), fire (flashes of colour), and scintillation (the play of light as the diamond moves). A finely cut diamond will appear lively and full of radiance, while a poorly cut stone may look dull even with excellent colour or clarity. Among the 4Cs, cut is often considered the most important, always prioritise it when selecting a diamond.

Click on the GIA slider above to compare diamond cut grades from Excellent to Poor.

Use the GIA slider above to see how diamond size increases as carat weight goes up.

Carat Weight - Weight, Not Size

Carat is the measure of a diamond’s weight, not its physical size. One carat equals exactly 200 milligrams. The term originates from the use of carob seeds as early weight standards in the 16th century. While larger diamonds are rarer and often command higher prices, carat weight is a matter of personal preference. A well-cut diamond of any size can make a striking impression, and thoughtful design can maximise its visual presence.

Diamond Shape

Though not officially one of the 4Cs, shape plays a major role in choosing a diamond. Shape refers to the stone’s outline - round, oval, emerald, pear, cushion, princess, and more. Each shape offers unique qualities: some maximise brilliance, others elongate the hand, and some may appear larger for their weight or hide inclusions effectively. Selecting the right shape is often about reflecting personal taste and style. Shown here are 11 of the most popular diamond shapes, but many more unique fancy cuts exist beyond this selection.

Diamond Certification

Every diamond should be accompanied by an independent grading report to confirm its quality. A certificate provides unbiased documentation of the 4Cs, giving you confidence in your choice. While very small diamonds under 0.30 carats are rarely certified, from 0.50 carats and above a GIA report becomes especially valuable, and for 1 carat and larger it is the industry standard. At Sara Peymanpour London, we work primarily with GIA-certified diamonds, recognised worldwide for their accuracy and integrity in grading. As a GIA Graduate Gemologist, Sara personally reviews each stone to ensure it meets the highest standards of beauty and authenticity.

How To Choose A Diamond?

Introduction

The 4Cs of Diamonds

Colour - From Colourless to Warmth

Clarity - Nature’s Fingerprint

Cut - The Spark of Life

Carat Weight - Weight, Not Size

Diamond Shape

Diamond Certification

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How To Choose A Diamond?

Introduction

The 4Cs of Diamonds

Colour - From Colourless to Warmth

Clarity - Nature’s Fingerprint

Cut - The Spark of Life

Carat Weight - Weight, Not Size

Diamond Shape

Diamond Certification

Not every story is told in public.

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