Class A Jewellers
Diamond Guide
Diamonds are among nature’s most treasured gems, admired for their brilliance, strength and timeless beauty. No two stones are the same, and choosing the right one comes down to understanding what makes each diamond unique. From shape and size to the 4Cs – cut, colour, clarity and carat – our guide will walk you through the essentials so you can make a confident and informed choice.
SHAPE
Diamonds come in a variety of shapes, each with its own distinct character and appeal. From classic rounds to elegant ovals or modern emerald cuts, the shape you choose is a reflection of your personal style and taste. Selecting the right diamond shape is a deeply personal decision, often guided by what feels most timeless, unique or true to you.
Round
The round brilliant cut is the most popular diamond shape. Perfectly symmetrical and balanced, round brilliants are cut with 56 facets to maximise fire and brilliance.
BROWSE ROUND DIAMOND ENGAGEMENT RINGS
Oval
An oval diamond is cut in the same style as a round brilliant to maximise fire and brilliance. The elongated, elliptical shape of the oval cut diamond can give the illusion of a larger stone and a longer finger.
Pear
With its tapered teardrop shape, pear diamonds combine elements of both the round brilliant and marquise cuts. Embracing a more unconventional silhouette, the pear diamond offers a refreshing twist on traditional diamond shapes.
BROWSE PEAR DIAMOND ENGAGEMENT RINGS
Marquise
The marquise diamond is characterised by its elongated ‘boat-like’ shape with pointed ends. This striking cut maximises the diamond's carat weight and surface area, creating the illusion of a larger stone. The unique silhouette of the marquise cut not only enhances the diamond's brilliance and fire, but can also elongate the finger.
BROWSE MARQUISE DIAMOND ENGAGEMENT RINGS
Cushion
Characterised by its square or rectangular shape with rounded corners, the cushion cut diamond is reminiscent of a pillow or cushion. This distinctive cut features large facets to enhance its brilliance, ensuring a mesmerising sparkle that captivates from every angle.
Radiant
The radiant cut diamond is typically rectangular in shape but can also be square. Complemented by cropped corners, this cut seamlessly combines the elongated shape of an emerald cut with the captivating brilliance and fire of a round brilliant.
Emerald
Emerald cut diamonds are traditionally rectangular shaped with bevelled corners and elongated, open facets which highlight the clarity of the diamond. The rows of narrow facets, known as step cuts, create a captivating 'hall of mirrors' effect. Ideal for minimalists, this unique cut offers a subtle sparkle, making it a perfect choice for those who appreciate understated elegance.
Princess
The princess cut diamond, featuring four pointed corners and a square shape, is renowned for its exceptional fire and scintillation. Its precisely angled facets maximise brilliance, creating a captivating sparkle.
THE 4CS
The 4Cs of Diamonds – Colour, Cut, Clarity and Carat Weight were established by the Gemological Institute of America (GIA) and are now recognised worldwide as the universal standard for describing and comparing diamond quality. Understanding the 4Cs will give you the knowledge and confidence to choose a diamond that best suits your style, preferences and budget.
COLOUR
When it comes to diamonds, colour actually refers to the absence of colour. The Gemological Institute of America (GIA) grades diamond colour on a scale from D (colourless) to Z (light colour). The less colour present, the rarer and more valuable the diamond becomes.
It’s important to note that this D–Z grading scale applies only to white diamonds. Fancy coloured diamonds, such as pinks and yellows, are graded on their own specialised colour scales.
CUT
Diamond cut is often mistaken for shape, but the two are quite different. While shape refers to the outline of the stone, cut describes the way a diamond’s facets are arranged and how they interact with light to create brilliance.
For round brilliant diamonds, the Gemological Institute of America (GIA) grades cut quality on a scale of Excellent, Very Good, Good, Fair and Poor. This grading system applies only to round diamonds, as their facet arrangement is uniquely standardised.
When assessing cut, three key visual effects are considered:
- Brightness – the white light reflected from the diamond
- Fire – the rainbow-coloured flashes seen across the facets
- Scintillation – the sparkle created by the pattern of light and dark areas
An Excellent cut diamond is precisely proportioned, allowing light to enter and reflect back through the top of the stone for maximum brilliance. By contrast, a poorly cut diamond – whether too shallow or too deep – can cause light to escape from the sides or bottom, leaving the stone looking dull or dark.
CLARITY
Clarity refers to the tiny natural imperfections found within or on the surface of a diamond – known as inclusions (internal) and blemishes (external). Most are only visible under 10× magnification and cannot be seen with the naked eye. Diamonds with very few or no imperfections are extremely rare, which makes them the most valuable.
The Gemological Institute of America (GIA) grades diamond clarity across 11 levels, grouped into six main categories:
- Flawless (FL) – No imperfections visible under 10× magnification. Extremely rare.
- Internally Flawless (IF) – No inclusions visible under 10× magnification.
- Very, Very Slightly Included (VVS1 and VVS2) – Minute inclusions, very difficult to detect under 10× magnification.
- Very Slightly Included (VS1 and VS2) – Minor inclusions, somewhat difficult to detect under 10× magnification.
- Slightly Included (SI1 and SI2) – Noticeable inclusions under 10× magnification.
- Included (I1, I2, I3) – Inclusions are obvious under 10× magnification and may also be visible to the naked eye.
CARAT WEIGHT
Carat is the unit used to measure a diamond’s weight, not its size. One carat equals 200 milligrams, and for accuracy, each carat is divided into 100 points. For example, a half-carat diamond has 50 points and may be referred to as a “fifty pointer.”
Because larger diamonds are more difficult to source, value increases with carat weight. However, weight alone does not determine price. Colour, clarity and cut all play an equally important role in a diamond’s overall beauty and worth.
What is a Lab Grown Diamond?
A lab grown diamond is a genuine diamond created in a laboratory under conditions that replicate the natural processes in which diamonds form within the earth.
There are two primary methods used: High Pressure, High Temperature (HPHT) and Chemical Vapour Deposition (CVD). Both techniques begin with a tiny “seed” – a thin slice of diamond about as thick as a human hair – which grows into a larger stone under carefully controlled conditions.
Because of this precision, lab grown diamonds often exhibit exceptional quality while sharing the same chemical, physical and optical properties as mined diamonds.
HPHT Method
A seed is placed amid pure graphite carbon and subjected to extreme temperature and pressure, which replicates the conditions deep within the earth where natural diamonds form. This process forms layers to the diamond over several days.
CVD Method
A diamond seed is placed into a vacuum chamber which is filled with carbon-rich gases and then heated to extreme temperature. Layers of carbon will begin to form around the seed diamond, growing a more substantial one.
Characteristics & Quality
Lab grown diamonds are chemically, physically and optically identical to mined diamonds. To the naked eye, they look the same – even experienced jewellers and gemmologists cannot distinguish between them without specialised testing equipment.
Value for Money
Lab grown diamonds are typically more affordable than mined diamonds, making them an attractive option for those seeking greater size or higher quality within their budget. In many cases, you can select a larger or finer lab grown diamond for a fraction of the cost of a comparable natural stone.
Eco-Friendly
Lab grown diamonds are created in highly controlled laboratory environments, meaning no mining is required. As a result, their production has far less impact on the environment compared to traditional diamond mining.
