Buying your first coloured gemstone is unlike buying almost any other piece of jewellery. Unlike diamonds, which are assessed using a standardised grading system, coloured gemstones are valued for their individuality. Every emerald, ruby or sapphire is one of a kind, shaped over millions of years beneath the Earth's surface.
Their rarity and beauty often come with a substantial price tag, making the purchase as much a financial investment as an emotional one. Understanding the factors that determine a gemstone's quality and value can help you buy with confidence, and choose a piece you'll cherish for decades.
Shape matters
Colour is one of the most important factors to consider when buying a coloured gemstone. Look for an even distribution of colour and strong saturation throughout the stone. Gems with consistent colour are not only rarer but also generally more valuable.
Equally important is the cut and proportion, which determine how light travels through the gemstone and influence its brilliance, symmetry and the way its colour is perceived. Before making a purchase, examine the gemstone in natural daylight rather than relying solely on showroom lighting, as artificial lights can enhance or alter the appearance of colour.
Don't fear inclusions
Many first-time buyers assume that the clearer the gemstone, the more valuable it is. While clarity is important, flawless coloured gemstones, particularly emeralds and rubies, are exceptionally rare. In fact, natural inclusions are often what distinguish a genuine gemstone from a synthetic or treated one.
These tiny internal features are formed over millions of years and offer a glimpse into a gemstone's natural journey. Rather than expecting perfection, buyers should focus on whether the inclusions affect the stone's brilliance, durability or overall beauty. If they don't, they should be seen as part of the gem's unique character rather than flaws. In the world of coloured gemstones, inclusions aren't always imperfections; they're often a reminder that no two stones are ever exactly alike.
Cs to consider
Many buyers are familiar with the diamond industry's four Cs—Colour, Clarity, Cut and Carat. While these remain important for coloured gemstones, they are only part of the story. Colour is often the most significant factor, while the cut determines how light interacts with the stone, influencing its brilliance and the way its colour is perceived. Carat, meanwhile, is simply a measure of weight and should be considered alongside the gemstone's overall quality rather than in isolation.
When buying coloured gemstones, it also pays to think beyond the traditional four Cs. Consider confidence: buying from a reputable jeweller who can explain the stone's provenance and any treatments it may have undergone. And always ask for a certified report from a recognised gemological laboratory, which verifies the gemstone's identity and key characteristics, helping you make an informed investment.
Shade card
The colour of a gemstone is often what draws people to it first, making it one of the most personal aspects of the buying journey. While factors such as cut, clarity and provenance are important, the shade you choose should ultimately reflect your taste and the way you intend to wear the piece. Whether you gravitate towards the deep green of an emerald, the velvety blue of a sapphire or the vivid red of a ruby, choose a colour you'll enjoy living with for years to come.
A coloured gemstone is a significant financial investment and, in many cases, an heirloom. Taking the time to find a stone whose colour truly resonates with you will ensure it remains just as meaningful decades from now.
Elena Basaglia, head (partnerships and product), Downstream, Gemfields.