The Gemstone Guide

A considered compendium to celebrating the world in colour.

Explore individuality through natural gemstones. From colour and beauty to rarity and durability, we explore the qualities that give coloured gemstones their lasting value and distinctive appeal.

Colour, without compromise.

Formed over millions of years under intense heat and pressure, gemstones are among nature’s most enduring masterpieces. Their journey, from deep within the Earth to the hands of our skilled gemmologists and lapidaries, is shaped by time, geology and expertise.

At SARAH & SEBASTIAN, every coloured gemstone is ethically sourced with provenance and transparency at the forefront. We work exclusively with natural gemstones, selected for their quality, integrity and traceable origins. From Australian sapphires to opals, each stone is chosen for its colour, depth and individual character. No two gemstones are ever the same. Each carries its own natural variations and story, making them a fitting symbol for a piece that is entirely unique.

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Beauty

Coloured gemstones offer a personal and expressive alternative to traditional diamonds, prized for their natural vibrancy and individuality. Unique tones, natural inclusions and distinctive colour patterns give each stone its own character, allowing beauty to feel personal rather than prescribed.

Durability

Durability is an important consideration when choosing a gemstone for everyday wear. While coloured gemstones vary in hardness, many are well suited to long-term wear when selected with care and thoughtfully set. Understanding a stone’s resilience ensures it remains beautiful over time.

Rarity

Rarity is inherent to coloured gemstones, shaped by limited formation, location and supply. Australian sapphires, for example, are renowned for their deep blues and distinctive colour variation, often showing green or yellow undertones that make each stone unique. Australian opals are equally rare, prized for their natural play of colour with no two opals ever displaying the same pattern or intensity.

Carat

Gemstones and diamonds of the same carat weight may appear different in size. Coloured gemstones are naturally denser and may look smaller than diamonds of equal weight. If visual scale is important to you, our gemmologists will help you select a stone whose dimensions align with your vision, beyond just the carat number.

Our Gemmologists

Our team includes trained gemmologists whose expertise shapes every engagement or milestone piece from the outset. They work closely with our sourcing partners to hand-select stones that meet both our standards and your vision, providing clarity, certification and confidence at every step.

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MOHS Scale of Hardness

The Mohs scale measures a gemstone’s resistance to scratching, offering a guide to durability and everyday wear. At SARAH & SEBASTIAN, diamonds, sapphires and rubies are selected for their hardness, while emeralds, pearls and Australian opals are chosen and set with care to honour their natural character. Understanding hardness helps ensure each stone is worn thoughtfully over time.

Opals

An opal is a natural gemstone formed from silica-rich water, prized for its rare ability to refract light into shifting flashes known as play-of-colour. No two opals are ever the same, each revealing its own pattern, depth and movement. It’s often said that an opal doesn’t get chosen, it chooses you.

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Pearls

A pearl forms organically when an oyster layers nacre around an irritant, creating a gem shaped entirely by nature. What sets a pearl apart is its lustre; the way light reflects and refracts to create a soft, iridescent glow and shimmering overtone that seems to shift as it moves.

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Frequently Asked Questions

Beyond their vibrant hues, gemstones carry a rich history of sentiment. Sapphires are traditionally associated with longevity, while Emeralds represent renewal and a deep connection to nature. Whether chosen for symbolism or a personal affinity for colour, a gemstone creates a modern heirloom that feels unmistakably yours.

We work with trusted suppliers who share our commitment to responsible sourcing. As a member of the Responsible Jewellery Council, we ensure our materials meet the highest international standards for human rights, social, and environmental responsibility.

Outside of the diamond, Sapphires and Rubies are the preeminent choice for durability. With a hardness of 9 on the Mohs scale, they are remarkably resistant to scratching and daily wear.

Yes, provided the stone is matched to your lifestyle. Diamonds, Sapphires and Rubies are engineered by nature for the everyday. Conversely, stones like Emeralds, Opals, and Pearls are more delicate; they require more thoughtful care to maintain their original radiance over time.

Birthstones

Your month, in colour.

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