Diamonds
19 Oct 2026
Whether youβre planning to gift your loved ones diamond jewellery, celebrate your new journey with a wedding ring or engagement ring, or simply want to make yourself feel special by gifting yourself, itβs essential to make sure that you can tell the quality of a diamond and whether what youβre paying is worth it.
This diamond buying guide will help you understand the 4 Cs of buying diamonds, which are four qualities to look out for that can help you assess a diamondβs value. This way, you can differentiate between real diamonds, lab-grown diamonds that possess natural diamondsβ properties while costing you less, and fake diamonds. This way, youβll only buy gemstones that are worth what theyβre priced at.
The 4 Cs Of Buying Diamonds
It is essential to have a clear idea about the 4 Cs of diamonds when youβre shopping for them, as these are the fundamentals that will ensure that you are paying the right price. The 4 Cs are as follows:
Carat
Diamond carats are the measurement of how much a diamond weighs. Diamond carat weight can be divided down to two decimal places to allow for very precise measurements of the stone's size.
Cut
Different diamond cuts can have a notable difference in the price of a diamond and the way it sparkles and reflects light. Differentiating between a low-grade and high-grade diamond cut can be a bit challenging. The preference should be a certified cut rather than a vendorβs individual cut.
Although 'cut' is normally referred to and thought of as its shape (such as oval, marquise, or pear), 'cut' actually refers to how well the diamond's facets interact with light. This is the most difficult of the 4 Cs to judge. The proportions of the diamond are judged on how well they create desirable properties such as its brightness, fire and scintillation.
'Brightness' refers to the amount of white light being reflected from the stone. 'Fire' refers to the scattering of white light into its different colours. βScintillationβ refers to its sparkle, or the pattern of light and dark areas produced by its reflections and facets.Β
Diamond Cut vs Diamond Shape
Although shape is a different aspect to consider in comparison to the different diamond cuts, it also has a notable price difference. Square diamonds are usually the least expensive compared to round, princess, and oval shapes. So, select your diamond shape wisely, especially if you are trying to save money.Β
Clarity
Diamond clarity is subjective. If you see it with your naked eye, you might not be able to tell the difference between a less clear and a clearer diamond. However, under the jewellerβs magnifying glass known as a loupe, you will be able to see a clear difference. So, it is up to you whether you want to purchase a clearer diamond or you pay less and buy a less clear one that seems clear to the naked eye.
Diamonds occur from carbon being exposed to immense amounts of heat and pressure within the earth. Due to this process, diamonds can be left with internal characteristics, which are called 'inclusions', and external characteristics called 'blemishes'.Β
What Is the Best Clarity for a Diamond
The diamond clarity scale has 11 different grades, as shown above. Like colour, it can be very hard to distinguish between grades with the naked eye. But be assured, they have been expertly judged. The higher up the scale towards flawless a diamond is, the more expensive it will likely be; again, this also depends on the other 3 Cs.
Colour
So, what colours are diamonds, and how can this affect their pricing? The colour of a diamond is divided into two categories. A diamond with a yellowish colour is usually less expensive than a pure, transparent diamond colour. On the other hand, coloured diamonds, including all the colours of the rainbow, black, grey, and white, are rare. Hence, they are more expensive and less commonly available than transparent diamonds.Β
The rating of colour is based on the absence of colour. The ratings go from a colourless diamond with a rating of D to a yellow diamond with a rating of Z. The colour distinctions between each rating can be incredibly subtle and unnoticeable to the untrained eye. However, these small differences can create large differences in both the quality and price of the stone.Β
How to Tell the Difference Between Fake and Real Diamonds
Diamonds are immensely popular, so buying them involves risk. Over the years, convincing imitations known as diamond simulants, such as cubic zirconia and moissanite, have become common, and they're easy to mistake for the real thing.
If you are wondering how to check fake diamond jewellery, the following tips will help you distinguish between real and fake diamonds:
Scratch Test: This is the most common test to identify a real diamond. Scratching the diamond against glass should scratch its surface if it is real because diamonds are the most durable substances on Earth.
Reading Test: A decent quality diamond is usually dense enough that you cannot read through it. Place the diamond on any newspaper or book; if you can easily read through it, there is a high chance that the diamond is fake.
Water Test: Diamonds are dense. So, if you add diamonds to a glass of water, real diamonds should sink to the bottom, whereas the fake ones will most probably float.
Fog Test: Fog a diamond with your mouth. If the fog doesnβt last more than a second or two, the diamond is highly likely a real one.
Sparkle Test: A real diamond will reflect grey colour tones when the light is reflected inside the stone and will reflect rainbow colours on the outside or the surface.
Are Lab-Grown Diamonds Worth Buying?
Lab-grown diamonds possess all of the same properties as real diamonds. These are made from pure carbon, just like a mined stone, and they share the same hardness and fire.
The only difference between them is where they form. A mined diamond takes shape deep within the earth over millions of years, whereas a lab-grown diamond forms in a controlled setting that recreates that same heat and pressure in a matter of weeks.
Because these two are physically identical, the tests above won't separate them, and even an experienced jeweller needs specialist equipment to tell them apart.
Lab-grown diamonds are graded on the same 4 Cs, so all of the advice above still applies to lab-grown choices too. Most of them come with a certificate from an independent grading laboratory, which gives you the same reassurance when you buy.Β
Lab-grown diamonds are assessed on cut and carat in a similar way as mined diamonds, so our advice on those two Cs still applies. However, colour and clarity are a little different. Most lab-grown diamonds fall within a very narrow range of colour and clarity, so some grading laboratories no longer use the same detailed scales they use for mined stones.
The Gemological Institute of America (GIA), for example, now gives lab-grown diamonds an overall βPremiumβ or βStandardβ description based on their colour, clarity, and cut, rather than individual grades such as a D colour or VS1 clarity. Coloured lab-grown diamonds sit outside this system and are assessed differently.
Other laboratories still grade lab-grown diamonds using the traditional 4 Cs scales, so how colour and clarity appear on a certificate can depend on which lab assessed the stone. Thereβs currently no single industry standard, and itβs an area thatβs still changing. Whichever diamond you choose, look for a certificate from an independent grading laboratory, and our team will be happy to talk you through what it means.
Theyβre a popular choice thanks to their great value, as lab-grown diamonds usually cost considerably less than mined stones of a similar grade. This means that you can stretch your budget to a larger carat weight or unique colour, which is handy if you've got your heart set on a statement engagement ring.
Why Consider the 4 Cs of Diamonds?
It doesnβt matter if you buy designer diamond rings, diamond necklaces, diamond earrings, or if you want to invest in some bespoke diamond designs. You have to pay attention to the 4 Cs of diamonds to ensure that you pay the right price for the right diamond.
Discussing the 4 Cs of diamonds with your seller will show that you know what you want, and theyβll be more vigilant while dealing with you. All in all, it is always advised to purchase diamonds from trusted, certified diamond sellers because not only do you have a better chance of finding a better diamond deal, but you can also trust their professional advice without having any concerns.
High-Quality Diamond Jewellery at Allum and Sidaway
At Allum and Sidaway, we have a wide variety of certified diamond jewellery to choose from, coming in all different shapes, colours, and sizes to suit your unique wants and needs. With over 80 years in the business, you can trust all of our diamonds to be of the best quality and at the best possible prices.
In our collection, you can also find a wide selection of lab-grown diamond jewellery, as we touched on above. Here, youβll find diamond jewellery with all of the same properties as natural diamonds, but with the options of greater carat weights and distinctive colours at more affordable price points.
If you would like to have more information on our jewellery pieces, then please email or phone one of our Allum and Sidaway stores; alternatively, you can contact us through our online form.
If youβre not sure about anything to do with the diamond jewellery youβre considering, ask one of our talented team members in store about an item. They'll be happy to talk you through the details of the diamond.
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Guides & Articles
13 Oct 2026
To make your Christmas shopping that much simpler this year, weβve put together a guide on the best jewellery Christmas gifts we most recommend to make this year extra special, broken down into different categories to suit every personality and budget.
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News
17 Sep 2026
Basingstokeβs new gem: Allum & Sidaway is coming to Festival Place
Weβre delighted to announce that Allum & Sidaway will be opening a new store at Festival Place, Basingstoke, in early 2027.
As a multi-award-winning, fourth-generation family jeweller, this opening marks an exciting new chapter for us. It also gives us the opportunity to introduce Allum & Sidaway to Basingstoke and create a welcoming new destination for beautiful jewellery, expert guidance and personal service.
Our story began in Shaftesbury, Dorset, in 1942. Since then, we have grown to six stores across the South, but the values on which our family business was founded remain at the heart of everything we do. We believe choosing jewellery should feel personal, enjoyable and memorable, and we take pride in helping every customer find a piece that feels right for them.
Our new Basingstoke store will bring that same approach to Festival Place. Designed as a luxurious yet inviting space, it will offer a carefully selected collection of engagement rings, wedding rings and fine jewellery, alongside much-loved brands including Nomination.
Whether you are searching for the perfect ring, celebrating a milestone, choosing a thoughtful gift or simply treating yourself, our team will be there to offer friendly, knowledgeable advice. We know that jewellery often carries a meaning far beyond the piece itself, which is why we take the time to listen, understand the occasion and help make every visit special.
The store will also offer professional ear piercing, giving customers another reason to visit us in a relaxed and welcoming setting.
For us, opening a new store is about more than creating a beautiful place to shop. It is about becoming part of the local community, building lasting relationships and being there for the moments that matter, from engagements and weddings to birthdays, anniversaries and everyday celebrations.
Our Managing Director, Jason Allum, says:
βWe are focused on creating an inviting and exciting new store, a luxurious space in which to choose those all important pieces and celebrate the moments that matter. We canβt wait to get to know the people of Basingstoke and immerse ourselves in the community.β
Weβre incredibly excited to bring Allum & Sidaway to Basingstoke and look forward to welcoming our first customers when the store opens in early 2027.
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Diamonds
06 Aug 2026
Since 1942, weβve been there for the moments that matter. Today, across six stores, Allum & Sidaway is proud to be the place to discover exceptional natural and lab-grown diamond jewellery, from beautifully chosen gifts to diamond engagement rings and wedding rings designed to mark lifeβs most significant chapters.
Diamonds have always sat at the very heart of our business, central to our heritage. Now, we are bringing that commitment into focus with the launch of our new brand promise; Β Your Diamond Destination
Whether you are drawn to the rarity of a natural diamond, the modern brilliance of lab-grown, the individuality of coloured diamonds or the elegance of a bespoke design, our qualified teams are here to guide you with expertise, clarity and care. Weβll talk you through the properties, possibilities and benefits of each stone, helping you choose with complete confidence. Coloured diamonds? Consider them found. Bespoke? Beautifully crafted. At Allum & Sidaway, every detail is considered, every question is welcome and every visit is shaped around delivering a truly 5* shopping experience.
At Allum & Sidaway, diamonds are not simply something we offer; they are something we stand for. With trusted expertise, carefully curated collections and exceptional customer service, we are proud to say it plainly: Allum & Sidaway isΒ Your Diamond Destination.
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Guides & Articles
30 Jul 2026
At Allum and Sidaway, weβve put together this guide on birthday gift ideas for her and him to help you choose a gift theyβll appreciate on the day and long into the future.Β
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Birthstone Jewellery
30 Jul 2026
The word sapphire, originating from the Greek word βsappheirosβ, is used to describe this mesmerising precious gemstone. Perhaps best known for its beautiful deep blue hues, it is a variety of the mineral corundum, consisting of aluminium oxide, with trace amounts of other elements, such as iron, titanium, chromium, copper, or magnesium.
This beautiful gemstone has a rich and fascinating history behind it and many significant meanings, which we explore in this blog below.
Sapphireβs Characteristics
Sapphire Hardness
The sapphire is among the most durable naturally occurring elements in the world, second only to diamond in strength and scoring 9 out of 10 on the Mohs scale β the scale used to score gemstones on their durability.
Sapphire Colour
While typically blue, sapphires can be found in many other colours. βFancyβ or "particoloured" sapphires are often found in yellow, orange, green, brown, purple, and violet hues, which can be intricately arranged into rainbow sapphire jewellery.
Red is the only colour of corundum that is not referred to as a sapphire, as these are considered to be rubies. The rarest of sapphires is a pinkish-orange colour called padparadscha, the Sanskrit word for lotus flower. The fascinating thing about sapphires and rubies is that these gemstones have the same chemical composition and the same mineral structure. Trace amounts of impurities determine if a gem corundum will be a brilliant red ruby or a beautiful blue sapphire.
Sapphires can exhibit a phenomenon called the βstar effect", or asterism. This occurs when needle-like inclusions create a six-ray star pattern on the surface of a cabochon-cut sapphire, often called a βstar sapphireβ.
Sapphires come in many sizes. They are readily available under 1 carat and can come as large as 20 carats in fine quality, but these stones are exceptionally rare.
The Sapphireβs Royal Connections
A royal favourite, stunning sapphires in dazzling regal blue tones, have been the choice of many monarchs throughout the ages and are perhaps the reason for the term βroyal blue'.
The famous Stuart Sapphire, a cabochon sapphire weighing 104 carats, has adorned royal crowns since 1214. It was so admired by the young Princess Victoria that she had it set into the Imperial State Crown for her coronation in 1838. The sapphire was then moved to the back of the Imperial State Crown in 1909, during the reign of King Edward VII, where it remains today, a treasured piece in the collection of the British Crown Jewels.Β
What Is the Birthstone for September? β Sapphiresβ Many Meanings
The blue sapphire is recognised as the birthstone for September. It is used to mark a 45th wedding anniversary and is the stone associated with a sapphire royal jubilee, which is celebrated after 65 years. The βBlue Sapphire Jubileeβ was the term used to mark the 65th anniversary of the reign of Queen Elizabeth II.Β
With its durability and a long history symbolising holiness, faith, peace and protection. Sapphires have become a popular choice for engagement rings, particularly in recent years.
Katherine Middleton, the Duchess of Cambridge, wears probably the most famous sapphire engagement ring in the world. The ring, formerly owned by Diana, Princess of Wales, features a 12-carat oval Ceylon sapphire surrounded by 14 solitaire diamonds, set in white gold.
This heavenly blue stone is surrounded by ancient myth and legend and is often attributed with mystical powers. Stories from ancient Persia depict the Earth sitting upon a huge blue sapphire pedestal. They believed that the stone reflected upwards toward the heavens, giving the sky its beautiful blue colour.
Sapphireβs Origins
Corundum, or sapphire, is found all over the world and is also used widely in industry for abrasive and cutting purposes due to its strength and durability.
Historically, the Kashmir region of India was noted for the production of famous Kashmir blue sapphires, while sources of production today include Sri Lanka, Myanmar, Tanzania, Australia, Cambodia, Thailand, Madagascar, and the USA.
The majority of fine gemstones are found in very small quantities in only a few places, most notably Sri Lanka, which has produced these precious gemstones for thousands of years and is still a major producer of the finest untreated stones in the world.
The βStar of Adamβ, the worldβs biggest blue star sapphire, was discovered in a mine in Sri Lanka in 2016. The gem weighed in at a massive 1,404.49 carats and was given an estimated value of at least $100 million. It is unlikely to be set into any kind of jewellery due to its size, and it appears destined to become a priceless museum piece.
Many of the worldβs largest and most valuable sapphires originated in Sri Lanka.
The Allure of Sapphire Jewellery
Some of the worldβs finest jewellery contains sapphires. These beautiful gemstones are equally as alluring when set into small pieces of jewellery, such as rings, necklaces, earrings, and brooches, as they are in the famous collections owned by film stars, princesses, and monarchs.
For timelessness, durability, and elegance, a sapphire is an excellent choice. A perfect gift for a September birthday, the deep, rich colours of this exquisite blue birthstone so accurately reflect the cool, crisp nature of this time of year.
Sapphire Jewellery at Allum & Sidaway
At Allum & Sidaway, we have an incredible selection of sapphire jewellery for you to discover, whether you want to celebrate a special moment in style or are simply looking for something to complement your day-to-day looks.
Purchase from our impressive range of sapphire rings, sapphire necklaces, or sapphire earrings online or visit one of our stores to take a look at our selection in person.
If youβd like to know anything more about our sapphire jewellery or any of our other choices from our diverse collection of jewellery, contact us today. A member of our experienced team will gladly assist you.
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Birthstone Jewellery
29 Jul 2026
When it comes to choosing aΒ Diamond, you may have heard about Laboratory GrownΒ Diamonds, both these andΒ NaturalΒ Diamonds are beautiful in their own way. When thinking about which to choose, it comes down to you as a buyer, what you value andΒ what youΒ are looking for.Β Β
For us at Allum and Sidaway, we will alwaysΒ championΒ Natural Diamonds for their rarity,Β intrinsicΒ beautyΒ andΒ their fascinatingΒ journey. Laboratory Grown diamonds have their place too andΒ itβsΒ important that you understand the difference between them and choose the one that is right for you.Β AsΒ YourΒ DiamondΒ Destination, our team of diamondΒ expertsΒ are on hand to help you find the perfect diamond for every occasion.Β
SoΒ which to choose?Β WeβveΒ outlined the differences below in ourΒ easy to understandΒ guideΒ to help you gain a better understanding ofΒ Natural andΒ LabΒ GrownΒ Diamonds.Β
The Creation of the DiamondΒ
The main difference between Natural and Lab Grown diamonds is how they are made. Natural diamonds are formed over billions of years,Β deep within the Earth. That rarity gives them a unique emotional and material value which we think adds to the romance of these exquisiteΒ stones. Laboratory Grown are created in a lab, just as their name suggests. They are grown using advanced technology that mimics natural conditions in just a few weeks!
What are the Diamonds Made of?Β
Both Natural and Laboratory Grown diamondsΒ are 100% carbon andΒ haveΒ exactly the sameΒ physical,Β chemicalΒ and opticalΒ properties. In fact to the nakedΒ eyeΒ they are visually identical. Trained gemmologists need specialist tools to tell them apart. As they are made of the same properties they both haveΒ exactly the sameΒ types of inclusionsΒ and lasting hardness.Β Β
Prices to suit all budgetsΒ
It'sΒ no secret that LabΒ GrownΒ Diamonds carry a cheaper priceΒ tag thanΒ NaturalΒ Diamonds,Β generally 30-70% cheaper. However, whilst natural diamondsβ valueΒ mayΒ increaseΒ overΒ time,Β the price ofΒ Lab GrownΒ DiamondsΒ hasΒ becomeΒ lowerΒ in the past couple of years,Β as productionΒ expands & improves,Β and they become more widelyΒ available .Β On this basis, resale value for Lab grown diamonds is uncertain.Β Β
SoΒ ifΒ youβreΒ looking at your diamond as an investment that you can treasure for generations to come, Natural Diamonds would be theΒ unparalleledΒ choice.Β
Lab Grown Diamonds is becoming a popular choice, not just for rings but for pendants,Β earringsΒ and bracelets too. Lab Grown makes for affordable prices so please do let our team know if you see something you like butΒ would preferΒ LaboratoryΒ Grown Diamonds.Β
Environmental differencesΒ
Laboratory Grown diamonds areΒ generally seenΒ as a more ethical and environmentally friendlyΒ option. That said, the energy used can vary depending on the production methods of the diamond.Β As you might imagine it takes an incredible amount of energy to grow a diamond. With naturallyΒ mined diamonds; there are different environmental factors to consider from the mining operation, but these are also often accompanied by educational, health, housing infrastructure that can improve the lives of whole communities.Β Β Β
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Jewellery
17 Jul 2026
Your Guide to Engagement Ring Shopping
Finding the perfect engagement ring is a beautiful milestone, and the experience should be just as memorable as the proposal itself. At Allum & Sidaway, we understand that navigating this purchase can feel daunting, so we have curated this guide to ensure a seamless and stress-free journey.
Our ultimate advice: donβt stress and leave the hard work to us.
Enjoy Personalised Consultations
Visit Our Boutiques:Β Step into one of our six beautiful stores for a relaxed, complimentary consultation over a drink with our knowledgeable team.
Curated Selections:Β By telling us all about your partner and sharing their lifestyle, personal aesthetic and your comfortable budget, our experts will curate a selection of rings tailored to your unique love story.
Expert Guidance:Β We will explain the all-important 4Cs to you, compare laboratory-grown and natural diamonds and explore various shapes and styles to ensure you are confident in your choice.
Exquisite Collections:Β Begin your search with our popular Engagement Collection, featuring premium D colour diamonds, or explore our extensive Laboratory Grown collection.
Expanded Sourcing: If you desire a specific metal, stone, or carat weight not currently on display, we can easily source options from our sister stores or provide custom quotes.
The Bespoke Experience
If you are looking for something truly one-of-a-kind, our bespoke service allows you to collaborate directly with our team and award-winning designer, Ivonna Allum, to bring your dream ring to life.
Planning Ahead
Sizing Solutions:Β Donβt worry about knowing the exact ring size; our in-store rings are typically a standard UK size M and can be expertly resized after your proposal for the perfect fit.
Shared Experiences:Β Whether you choose to plan a surprise or shop together as a couple, we promise a romantic and unforgettable experience.
Flexible Financing:Β We offer Interest Free Credit options to help you comfortably spread the cost of your purchase.
Idea Gathering:Β Before your visit, explore our website to browse our collections and take a look at our Engagement Ring Builder to view styles and live pricing.
To ensure a discreet and fully dedicated experience, we highly recommend booking an appointment at your local store. Our team will be awaiting your arrival with some gorgeous rings ready to show you based on the ideas you shared when booking.
We look forward to welcoming you and playing a small part in your beautiful new chapter.
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News
14 Jul 2026
Mission Beach CleanThis month we made it our mission to help clean up one of our gorgeous local beaches, Durley Chine in Bournemouth. Litter pickers and sun cream in hand some of our amazing team cleaned up the beach. We also conducted a litter survey which helps marine charities globally understand which types of pollutants are accumulating in our natural spaces.Β
The coast plays a significant role in the lives of our staff, clients and communities, so we believe itβs our responsibility to help look after our cherished spaces. This is why we have partnered with the amazing Marine Conservation Society once again, to help make a difference.Β
Thank you so much to our teams, families and friends that help year after year.Β
To help support this amazing charity we have specially curated a collection of all things coastal. 20% of our Marine collection will be donated to the Marine Conservation Society. You can browse the collection by clicking here.
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