Diamond Buying Guide

DIAMOND BUYING GUIDE

How to Choose the Right Diamond with Confidence

Buying a diamond should feel exciting, not confusing. A grading report provides important technical information, but choosing the right diamond also involves understanding how the stone looks, how it performs in different lighting and which qualities matter most to you.

With 18 years of experience in diamonds and fine jewellery, Dina Fine Jewellery offers honest, personal guidance to help you compare natural and lab-grown diamonds and make a confident decision.

This guide explains diamond shape, cut, colour, clarity, carat weight, certification and the additional details that can affect beauty and value.

START WITH YOUR PRIORITIES

Before comparing diamonds, consider what matters most to you:

• Overall budget
• Natural or lab-grown diamond
• Preferred diamond shape
• Brilliance and sparkle
• Carat weight and visible size
• Colour and clarity
• Ring style and metal
• Certification

There is no fixed amount that you must spend. Choose a comfortable budget and focus on finding the most beautiful diamond within it. A knowledgeable jeweller should respect your budget and explain the available options without pressure.

  1. CHOOSE YOUR DIAMOND SHAPE

Shape describes the diamond’s outline when viewed from above. It is different from cut quality, which describes how successfully the diamond interacts with light.

Popular shapes include:

Round Brilliant

The classic and most popular choice. Its facet arrangement is designed to produce exceptional brilliance, fire and sparkle.

Oval

An elegant, elongated shape that can appear larger than a round diamond of the same carat weight. Each oval should be checked for its proportions and the visibility of any bow-tie effect.

Emerald Cut

A sophisticated rectangular shape with long, step-cut facets. Emerald cuts produce elegant flashes of light rather than the intense sparkle of brilliant cuts. Because of their open appearance, colour and clarity can be easier to notice.

Cushion Cut

A square or rectangular shape with rounded corners. Cushion diamonds range from soft, romantic styles to modern elongated designs.

Pear Shape

A combination of round and marquise characteristics, creating a graceful teardrop shape. Symmetry and the shape of the point are important.

Radiant Cut

A rectangular or square diamond combining the outline of an emerald cut with brilliant-style faceting and lively sparkle.

Marquise

A distinctive elongated shape with pointed ends. Its large face-up appearance can make it look impressive for its carat weight.

Princess Cut

A modern square shape with brilliant faceting. Princess cuts offer strong sparkle and a clean, contemporary appearance.

The best shape is the one you genuinely enjoy. Wherever possible, compare shapes in person or view clear 360-degree videos before deciding.

  1. CUT: THE KEY TO BRILLIANCE

Of the 4Cs, cut usually has the greatest influence on how much a diamond sparkles.

Cut quality is not the same as diamond shape. It refers to the proportions, symmetry, polish and arrangement of facets that control how light enters and leaves the diamond.

A beautifully cut diamond returns light through the top of the stone, producing:

• Brilliance – white light reflected from the diamond
• Fire – flashes of spectral colour
• Scintillation – sparkle created as the diamond or viewer moves

A diamond with high colour and clarity can still appear dull if it is poorly cut. For this reason, we normally recommend prioritising cut quality before paying for colour or clarity grades that may not be visible without magnification.

For a round brilliant diamond, the grading report normally provides an overall cut grade. Fancy shapes such as oval, pear, emerald, cushion and radiant diamonds require more visual assessment because their beauty cannot always be judged by one grade or a set of measurements alone.

Always examine the diamond’s light performance, symmetry and overall appearance rather than relying only on the certificate.

  1. COLOUR: FROM COLOURLESS TO WARM

For standard white diamonds, colour is graded from D to Z:

• D–F: Colourless
• G–J: Near colourless
• K–M: Faint colour
• N–Z: Increasingly noticeable yellow or brown tones

Small differences between neighbouring colour grades can be difficult to see without placing diamonds side by side under controlled lighting.

The ring metal also affects how colour appears:

• Platinum and white gold can make warmth more noticeable.
• Yellow and rose gold can complement diamonds with warmer tones.
• Larger diamonds and step cuts, such as emerald and Asscher cuts, may reveal colour more easily.

A higher colour grade is not automatically the best choice for every customer. The aim is to select a diamond that looks beautiful in your chosen setting while using your budget effectively.

Fancy-coloured diamonds, including yellow, pink and blue diamonds, are assessed differently. Their value is influenced by the strength, tone and distribution of colour.

  1. CLARITY: UNDERSTANDING INCLUSIONS

Clarity measures the presence of internal features called inclusions and surface features called blemishes.

The clarity scale includes:

• FL – Flawless
• IF – Internally Flawless
• VVS1 and VVS2 – Very, Very Slightly Included
• VS1 and VS2 – Very Slightly Included
• SI1 and SI2 – Slightly Included
• I1, I2 and I3 – Included

Diamonds are clarity-graded under 10-times magnification. Many characteristics affecting the grade may not be visible to the unaided eye.

Rather than paying only for the highest grade, look for an eye-clean diamond: a stone with no distracting inclusions visible during normal viewing.

The position, colour and type of inclusion are as important as the grade. An inclusion beneath the centre table may be more noticeable than one near the edge. Step-cut diamonds may reveal inclusions more easily than brilliant-cut diamonds, so they can benefit from careful clarity selection.

We assess each diamond individually because two stones with the same clarity grade may look very different.

  1. CARAT: WEIGHT AND VISIBLE SIZE

Carat measures weight, not visible diameter. One carat equals 0.20 grams.

Two diamonds with the same carat weight can appear different in size because of their:

• Shape
• Depth
• Proportions
• Face-up measurements
• Cut quality

A deeply cut diamond may carry more weight below the setting and appear smaller from above. An elongated oval, pear, marquise or radiant diamond may appear larger than a round diamond of equal weight because its surface area is distributed differently.

Diamond prices often increase significantly at popular weight points such as 0.50, 1.00, 1.50 and 2.00 carats. A diamond slightly below one of these weights may offer attractive value while appearing almost identical in size.

Never choose carat weight alone. Consider the diamond’s measurements, proportions and beauty together.

  1. NATURAL OR LAB-GROWN DIAMONDS

Natural diamonds are formed deep within the earth over an extremely long geological period.

Lab-grown diamonds are produced using advanced technology, commonly through Chemical Vapour Deposition (CVD) or High Pressure High Temperature (HPHT) processes.

Lab-grown diamonds are genuine diamonds. They have essentially the same chemical, physical and optical properties as natural diamonds, but their origins and market characteristics are different.

Natural diamonds may appeal to customers who value rarity, geological origin and tradition. Lab-grown diamonds often allow customers to choose a larger size or higher specifications within the same budget.

Neither option is right for everyone. We explain both clearly so you can choose according to your preferences, values and budget.

A lab-grown diamond should never be represented as natural. Its origin must be clearly disclosed and recorded on the relevant grading report.

  1. DIAMOND CERTIFICATION

A diamond grading report provides an independent assessment of the diamond’s characteristics.

It can include:

• Natural or laboratory-grown origin
• Shape and cutting style
• Measurements
• Carat weight
• Colour grade
• Clarity grade
• Cut grade where applicable
• Polish and symmetry
• Fluorescence
• Proportions
• Clarity characteristics
• Report number

GIA and IGI are among the best-known laboratories used for diamond grading. The report number may also be laser-inscribed on the diamond’s girdle and can be checked against the laboratory’s online records.

A grading report describes the diamond, but it does not replace visual inspection. Two diamonds with similar certificates can differ in sparkle, transparency and overall appearance.

  1. POLISH AND SYMMETRY

Polish refers to the quality and smoothness of a diamond’s finished facets.

Symmetry describes how precisely the facets align with one another.

Good polish and symmetry support attractive light performance. However, these grades should be considered alongside the diamond’s overall proportions and appearance rather than judged in isolation.

  1. FLUORESCENCE

Fluorescence is the visible light that some diamonds emit when exposed to ultraviolet light. Blue is the most common fluorescence colour.

Fluorescence is not automatically good or bad. In many diamonds, it has little noticeable effect during normal wear. With some stones, particularly those graded strong or very strong, it is sensible to inspect the diamond in different lighting conditions and check that it remains bright and transparent.

  1. LENGTH-TO-WIDTH RATIO

For elongated shapes, the length-to-width ratio affects the diamond’s outline.

A lower ratio creates a wider appearance, while a higher ratio creates a longer, more slender shape.

There is no single perfect ratio. The right proportion depends on personal taste, but the diamond should look balanced and symmetrical.

  1. BOW-TIE EFFECT

Oval, pear, marquise and some elongated cushion or radiant diamonds may show a dark bow-tie-shaped area across the centre.

A slight bow tie is common and may add contrast. A very dark or distracting bow tie can reduce the diamond’s overall beauty.

This feature is not fully explained by the grading report, making photographs, videos or in-person inspection particularly important.

  1. MATCHING THE DIAMOND TO THE SETTING

The ring design can change how a diamond looks and how securely it is held.

Solitaire Setting

Places full attention on the centre diamond and provides a timeless appearance.

Hidden Halo

Adds a discreet row of diamonds beneath the centre stone for extra detail from the side.

Halo Setting

Surrounds the centre diamond with smaller stones, increasing sparkle and its overall visual presence.

Trilogy Setting

Features a centre stone with two side stones, often symbolising the past, present and future.

Shoulder-Set Band

Adds diamonds along the band to complement the centre stone.

Bezel Setting

Surrounds the diamond with a rim of metal, offering a modern appearance and additional protection.

The setting should suit the wearer’s lifestyle as well as their preferred style. A beautiful ring must also be comfortable, secure and practical for regular wear.

  1. HOW TO USE YOUR BUDGET EFFECTIVELY

If brilliance is most important:

Prioritise cut quality and visual light performance.

If visible size is most important:

Compare face-up measurements, consider elongated shapes and explore lab-grown options.

If a colourless appearance is most important:

Prioritise colour while considering the chosen metal and diamond shape.

If purity is most important:

Consider higher clarity grades while confirming whether the difference is visible without magnification.

If overall value is most important:

Choose a beautifully cut, eye-clean diamond with a colour grade that looks attractive in the finished ring. Avoid paying for qualities you cannot appreciate visually unless those grades are personally important to you.

  1. QUESTIONS TO ASK BEFORE BUYING

Before selecting a diamond, ask:

• Is the diamond natural or lab-grown?
• Is it independently graded?
• Can I verify the report number?
• Is the diamond eye-clean?
• Does it look bright in different lighting?
• Are there any noticeable bow ties, dark areas or transparency issues?
• How does its face-up size compare with its carat weight?
• Does the setting complement and protect the diamond?
• What are the resizing, care, warranty and returns arrangements?
• Can I inspect the diamond or view a clear video before purchasing?

OUR EXPERT RECOMMENDATION

Do not choose a diamond from the grading report alone.

Use the report to understand and compare quality, then judge the actual diamond for brilliance, transparency, proportions and overall beauty. The best diamond is not necessarily the one with the highest grades. It is the diamond that balances beauty, quality, size and price according to your priorities.

PERSONAL DIAMOND GUIDANCE IN HATTON GARDEN

With 18 years of experience in diamonds and fine jewellery, Dina Fine Jewellery provides clear, honest and personalised advice.

Visit our Hatton Garden boutique to compare natural and lab-grown diamonds, explore engagement-ring designs and discuss a bespoke piece made around your chosen diamond.

Book a private consultation with Dina Fine Jewellery and let us help you select a diamond with confidence.