Free shipping on all orders over £100, special delivery!

0% Interest free credit available

Diamond Buying Guide - The 4 C's

Diamonds are a symbol of everlasting pure love, strength, and trust. People believe that diamonds fill the negative space in one's heart. 

You might be planning to gift your loved ones diamond jewellery, or planning to celebrate your new life’s journey with a diamond wedding ring or engagement ring, or simply wanting to make yourself feel special by gifting yourself some stunning diamond jewellery with your hard-earned cash. No matter what the reason is, buying a diamond can be stressful, especially if you are new to diamond purchasing.

This diamond buying guide will not only help you understand the 4 C’s of buying diamonds, but it will also help you differentiate between real and fake diamonds so that you can buy the best diamond jewellery that you and your loved ones can cherish for life.

The 4 C’s Of Buying Diamonds

It is essential to have a clear idea about the 4 C’s of diamonds. These are the fundamentals that will assure that you are paying the right price. 


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 stones size. 

Generally, the larger the carat size the higher the price of the diamond. However, this might not always be true depending on the values of the other C’s.


Cut 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 vendor’s individual cut.

Although, the shape is a different category; however, the shape of a diamond also has a notable price difference. Square diamonds are usually the least expensive compared to round, princess and oval shape. So, select your diamond shape wisely, especially, if you are trying to save money. 

Although cut is normally referred to and thought of as its shape (oval, marquise, pear etc). Cut actually refers to how well the diamonds facets interact with light. This is the most difficult of the 4C’s 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 and scintillation refers to its sparkle, or the pattern of light and dark areas produced by its reflections and facets. 

The cut of a diamond is also judged by how well and how proportionate all of its facets are.


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 clearer diamond. However, under the jeweller’s magnifying glass known as the “Virtual Loupe,” you will be able to see a clear difference. So, it is on you whether you want to purchase a clearer diamond or you will 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 internal characteristics which are called inclusions and external characteristics called blemishes. 

The diamond clarity scale has 11 different grades, which you can see 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 3C’s.


 The colour of a diamond is divided into two categories. A diamond with a yellowish colour is usually less expensive to the 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 rarely available compared to a transparent diamond. 

It doesn’t matter if you buy designer diamond rings, diamond necklaces, diamond earrings or you want to invest in some bespoke diamond designs. You have to pay importance to the 4 C’s of diamonds to ensure that you pay the right price for the right diamond.


Discussing the 4 C’s of diamonds with the seller will show that you know what you want and they’ll 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 that you have a better chance of finding a better diamond deal, but you would also be able to trust their professional advice without having any second thoughts in your mind.

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 quality and price of the stone. 

Fake vs. Real Diamonds

Diamonds are immensely popular, so buying diamond involves risk because through the years manufacturers have mastered the manufacturing of “real-looking fake” diamond crystals that are usually known as Simulated Diamond or Imitation Diamond. Most people also confuse cubic zircon with diamonds. So, if you are wondering how to check fake diamond jewellery, the following five tips will help you identify real vs. fake diamond:

  • Scratch Test: This is the most common test to identify a real diamond. Scratching the diamond against glass should scratch the surface of the glass 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 are high chances 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 doesn’t 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.

  • Heat Test: Heat the stone with a lighter for approx. 30 secs and then place the stone in a glass of cold water. A real diamond is hard enough to bear the temperature change shock. A fake one will crack or completely shatter into pieces. Although this test sounds easy and reliable, it involves high-risk factor, and you may end up losing your precious stone.

  • UV Light Test: If you want a highly reliable test that involves the least amount of risk. Then you should go for the UV light or black light test. A real diamond with fluorescent should turn blue under the UV or black light. 

At Allum and Sidaway we have a wide variety of certified diamonds to choose from coming in all different shapes, colours and sizes to suit everyone’s wants and needs. If you would like to have more information on one of our diamonds then please email or phone one of our stores, alternatively you can use our contact form

If you’re not sure, ask one of our talented team members in store about an item and they will be happy to talk you through the details of the diamond.


Shop All Diamond Jewellery

Previous post
Next post