Gemstone
Buying Guide
Whether you are choosing a diamond for an engagement ring or selecting a coloured gemstone as a gift, the range of options can feel overwhelming. This guide walks you through the key factors that affect a gemstone’s beauty and value, so you can shop with confidence and find the perfect stone for your budget.
At Aardvark Jewellery, every gemstone we sell is hand-selected for quality and ethically sourced from trusted suppliers. From our workshop in Birmingham’s Jewellery Quarter, we help customers find exceptional stones — whether that is a brilliant diamond for an engagement ring or a vivid sapphire for a bespoke pendant. This guide distils everything we’ve learned into practical advice you can use today.
The Four Cs
The Four Cs are the universal standard for assessing diamond quality, but they are also a useful framework for understanding most gemstones. Here is what each one means in plain terms.
Cut
How well a gemstone has been shaped and faceted. A well-cut stone reflects light beautifully, giving it that sought-after sparkle. Cut is often the most important factor — even a high-quality stone can look dull if poorly cut. Common shapes include round brilliant, oval, cushion, emerald, and pear.
Colour
For diamonds, the scale runs from D (colourless, most rare) to Z (noticeable warmth). Diamonds in the G–I range look colourless to the naked eye and offer excellent value. For sapphires, emeralds, and rubies, vivid and evenly distributed colour is generally the most valuable. However, what you love the most is key, and many people today find mixed or more muted colours the most attractive. When it comes to coloured stones, it’s all about personal preference!
Clarity
The presence of tiny natural imperfections called inclusions — nature’s fingerprints. The scale ranges from Flawless to Included. As standard, for our white lab grown diamonds, we offer VS1 clarity. We feel this is the optimum clarity for value. For coloured gems, clarity is measured differently and is generally considered less important than colour and cut.
Carat Weight
A measure of weight, not size. One carat equals 0.2 g. Larger stones are rarer and more expensive per carat, but a well-cut smaller stone can appear larger and more brilliant than a poorly cut bigger one. Consider all four Cs together rather than carat alone.
Popular Gemstones
While the world of gemstones is wonderfully diverse, four stones remain the most popular choices for fine jewellery. Here is a quick overview of each.
Diamonds
The hardest natural material on earth, scoring 10 on the Mohs scale. Their exceptional brilliance and durability make them the classic choice for engagement rings. Natural diamonds are formed deep within the earth over billions of years, and each one is genuinely unique. Lab grown diamonds are the environmental and ethical option, with each one painstakingly grown in a laboratory over a period of weeks or months.
Sapphires
Available in virtually every colour — from soft pink and golden yellow to vibrant teal. They score 9 on the Mohs hardness scale, making them excellent for rings worn daily. Bi colour and parti (multi colour) sapphires are particularly prized for their uniqueness.
Emeralds
Treasured for their rich, verdant green. They belong to the beryl mineral family and typically contain natural inclusions known as their jardin (“garden”). Slightly softer than sapphires but still suitable for engagement rings providing the inclusions do not affect the overall structure of the stone.
Alexandrites
Alexandrite is one of the world’s rarest and most fascinating gemstones, prized for its dramatic colour change. In daylight it typically appears green to bluish-green, while under warm incandescent light it shifts to red, purplish-red, or raspberry tones. A variety of chrysoberyl, alexandrite was first discovered in Russia in the 1830s. Nowadays, lab grown Alexandrites are available and match the colour change properties of the very best naturals.
Lab-Grown vs Natural Gemstones
Lab-grown gemstones are chemically and optically identical to their natural counterparts but are created in controlled laboratory environments rather than mined from the earth. They are typically much more affordable than equivalent natural stones and have a smaller environmental footprint.
Natural gemstones, on the other hand, carry the romance of having formed over millions or billions of years. They also tend to hold their value better over time. The right choice depends on your priorities — there is no wrong answer.
We have written a detailed comparison of lab-grown and natural gemstones if you would like to explore this topic further.
Certification & Grading
A gemstone certificate is an independent assessment of a stone’s quality, carried out by a qualified gemologist. It documents the Four Cs and any treatments the stone has undergone, giving you an objective record of exactly what you are buying.
The most widely recognised grading laboratory is the International Gemological Institute (IGI), which follows rigorous, standardised methodologies.
At Aardvark Jewellery, every diamond over 0.5 carats comes with an independent gemologist certification. This means you can buy with complete confidence, knowing your stone has been assessed by an impartial expert.
Ethical Sourcing
We believe beautiful jewellery should never come at the cost of people or the planet. Every gemstone we sell is ethically sourced and conflict-free. We work with trusted suppliers who share our commitment to responsible practices and full traceability throughout the supply chain.
From our workshop in the Birmingham Jewellery Quarter, we have built long-standing relationships with miners, cutters, and dealers who adhere to the highest ethical standards.
Key Takeaways
Prioritise cut — of the Four Cs, cut has the greatest impact on a gemstone’s sparkle and brilliance.
Balance the Four Cs — consider cut, colour, clarity, and carat together rather than focusing on any single factor.
Insist on certification — an independent certificate from IGI gives you an objective record of your stone’s quality.
Know your options — lab-grown stones are chemically identical and offer outstanding value; natural stones carry timeless romance.
Buy ethically — every Aardvark gemstone is conflict-free with full supply-chain traceability.