The Diamond Guide

Our complete compendium to the gemstone that marks a lifetime. The Diamond Guide brings together everything you need to know about SARAH & SEBASTIAN natural diamonds, from ethical sourcing and GIA certification to the Four Cs and the expertise behind every stone.

The Four C's

The Four Cs - cut, clarity, colour and carat weight, are often the first reference point when exploring diamonds. Together, they provide a framework for understanding quality and individuality. Beyond the specifications, choosing a diamond is also about instinct and recognising the stone that feels right, guided by considered advice and experience.

CUT

CLARITY

CARAT

COLOUR

What Is Diamond Cut?

Cut is the most influential of the Four Cs, shaping how a diamond captures and reflects light. Defined by proportion, balance and polish, it directly impacts a stone’s brightness and overall beauty. At SARAH & SEBASTIAN, every diamond is carefully selected for exceptional cut quality. Round diamonds are always Triple Excellent, while all other shapes are graded Excellent to Very Good, ensuring light, not size alone, defines its impact.

Why is cut so important in a diamond?

When a stone is cut with imprecise proportions or alignment, light escapes through the sides or base, resulting in a muted appearance regardless of colour or clarity. A well-cut diamond, in contrast, reflects and refracts light back through the crown, creating brightness, fire and scintillation. For this reason, SARAH & SEBASTIAN prioritises cut quality in every diamond selection, ensuring each stone is proportioned to maximise light return rather than relying on carat weight alone.

What is diamond colour?

Diamond colour refers to the natural presence of tint within a white diamond. It is graded on an industry-standard scale from D to Z, with D representing the most colourless and rare stones. The closer a diamond is to colourless, the more exceptional its beauty and value.

At SARAH & SEBASTIAN, we select only natural diamonds graded between D and G, chosen for their refined appearance and clear, luminous presence once set.

Why is colour important?

Colour is the second most important of the Four Cs, as it directly influences a diamond’s overall appearance. Diamonds with a low grade can show a noticeable yellow tinge, particularly in natural light, which can affect how white and brilliant a stone appears.

At SARAH & SEBASTIAN, each diamond is individually assessed, and stones with strong or visually disruptive fluorescence are not selected, ensuring your SARAH & SEBASTIAN diamond maintains clarity and brightness.

Diamond Specialists

From your first consultation, our in-storeSpecialists guide you through stone selection, cut, clarity and design preferences. Whether you're exploring signature engagement styles or a bespoke creation, you receive personalised guidance grounded in technical knowledge and genuine care.

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What is Diamond Clarity?

Clarity refers to the natural characteristics formed as a diamond develops under extreme heat and pressure deep within the Earth.

These internal inclusions and surface features are assessed under magnification, based on their size, number and placement. While a Flawless diamond shows no visible characteristics under 10× magnification, it’s often the balance of clarity and overall beauty that matters most.

We individually select our diamonds ensuring that inclusions are not immediately visible to the eye and do not compromise the stone’s appearance.

Does clarity really matter in a diamond?

Yes. Clarity influences how effectively light travels through a diamond, directly affecting its brightness and overall appearance. Diamonds with lower clarity grades can appear hazy or dull, as inclusions disrupt the passage and return of light, reducing visual performance.

“We select diamonds with clarity levels that allow light to move freely through the stone, so its brightness and presence remain uncompromised.”


– Sarah Gittoes, Creative Director

What is a Diamond Carat?

Carat is a measure of weight, not visual size, with one carat equal to 0.2 grams.

Two diamonds of the same carat weight can appear very different depending on how they are cut, proportioned and finished.

Rather than prioritising weight alone, SARAH & SEBASTIAN diamonds are chosen for balance, symmetry and beauty. We believe a diamond’s presence should feel considered and harmonious and it’s this balance (not size in isolation) that gives a diamond its lasting appeal.

Are our diamonds ethically sourced?

The beauty of a SARAH & SEBASTIAN diamond extends to the integrity of its journey. As a member of the Responsible Jewellery Council, we are committed to sourcing natural, conflict-free diamonds from suppliers who uphold the highest ethical and environmental standards.

Every stone is compliant with the Kimberley Process and individually GIA-certified, ensuring a transparent record of its history. This rigorous selection process guarantees that your diamond is as responsible as it is rare.

Frequently Asked Questions

Every engagement ring is handcrafted in our Sydney studio. Please allow eight weeks for our specialist to source your natural diamond and complete your piece. If you select from our limited, ready-to-set stockholding, your ring will be ready for dispatch in 20 business days.

Through our bespoke service, you may adapt our signature silhouettes. Our specialists will guide you through selecting unique stones and alloy finishes to ensure the final piece remains true to your vision and our brand DNA.

We offer a 36-month manufacturing warranty on all engagement rings. This is supported by our care service, which includes professional cleaning and stone setting examinations to maintain the visual integrity of your piece over time.

There’s no formula. Only you know what feels right—for your story, your partner, and your budget. Our engagement specialists are here to guide you through our thoughtfully crafted designs at every price point, ensuring quality at every level of investment.