When you’re buying a diamond ring, the ‘carat’ of the centre stone is likely to be one of the biggest deciding factors in which ring you choose.
Not only does it affect what the ring looks like, it’s also one of the biggest determinants of the cost of the diamond.
By the end of this guide, you’ll have a clear understanding of what diamond carat is all about and how to make the best choice for your engagement ring.
What is Diamond Carat?
Contrary to what many people think, ‘carat’ isn’t a measure of how ‘big’ a diamond is, instead it’s a measure of how much a diamond weighs.
One carat is equivalent to 0.2 grams or 200 milligrams.
So, while carat weight can give you a general idea of how large the stone will appear, it isn’t a foolproof guide. Two diamonds can weigh the same but have different shapes and will therefore look different sizes when mounted in a ring.
Where ‘carat’ came from
The term “carat” has its origins in ancient times when carob seeds were used as a standard for weighing precious gemstones.
Today, the carat system is a universally accepted method for measuring a diamond’s weight, with each carat being broken down into the smaller unit of ‘points’e.g. a 0.5 carat diamond might be called a ’50 pointer’.
Why diamond carat is important
Carat is an important factor in determining a diamond’s value, as larger diamonds are generally than smaller ones.
However, it’s crucial to remember that carat is just one aspect of a diamond’s overall quality and should be considered alongside the other 4 C – cut, clarity and colour – as well as a host of other factors too.
Diamond Size vs Carat Weight
Though carat weight is related to a diamond’s size, it’s important to understand that it’s not the same thing.
A diamond’s size refers to its dimensions (length, width, and depth), and different diamonds of the same carat weight can look quite different.
Looking at the example below, the diamond on the right is cut to be deeper than the diamond on the right.
Equally, two diamonds of the same shape and carat weight can look quite different if they carry their weight in different places. A 1 carat oval shaped diamond that is cut deeper may look significantly smaller than one that is cut shallower:
For example, some diamond shapes have more ‘spread’ than others, so a 1 carat oval will generally look larger than a 1 carat round diamond.
How Diamond Carat Affects Prices
Carat weight plays a significant role in determining a diamond’s value and as a general rule, the higher the carat weight, the more valuable it is.
However, it’s important to note that diamond prices don’t increase in a straight line with carat weight. Instead, prices jump at popular carat weights e.g. 0.5 carats, 1 carat, 1.5 carats, etc, due to higher demand for these sizes.
For example, a 1-carat diamond is likely to cost significantly more than a 0.95 carat diamond of the same quality, even though the actual difference in size is minimal.
Balancing Carat Weight with Cut, Clarity, and Colour
While carat weight is an important factor to consider when choosing a diamond, it’s important to remember that it’s just one aspect of a diamond’s overall quality.
To strike the best balance between value and appearance for your engagement ring, you’ll need to also consider the other Cs: cut, clarity, and colour.
A well-cut diamond will sparkle more brilliantly, and sometimes even appear appear larger than a poorly cut diamond of the same carat weight. Prioritising cut quality is an excellent way to maximise the beauty of your diamond, even if it means opting for a slightly smaller carat weight.
Clarity and colour are also important factors to consider. For example, you may choose to sacrifice a bit of carat weight in favour of a higher clarity or colour grade, to ensure that the diamond is a good all-rounder.
Lastly, there’s an additional C to consider – Cost. Buying a diamond ring is
How to Choose the Right Carat Weight for Your Engagement Ring
There are several things to think about then it comes to choosing what carat weight is right for your engagement ring:
Personal preferences and style: Consider your partner’s tastes and preferences when selecting a diamond. Some people may prefer a larger diamond and be happy to sacrificen colour or clarity, while, while others may prefer a more modest and understated look, but with more of a focus on the quality of the diamond.
Finger size and proportion: Take into account your partner’s finger size and proportion when selecting a carat weight. A larger diamond might look overwhelming on a smaller finger, while a smaller diamond could appear underwhelming on a larger finger. Diamond shape can also make a big difference here – as mentioned earlier, elongated shapes like oval diamonds can look larger than round or princess cuts.
Lifestyle and daily activities: If the ring-wearer has an active lifestyle or a job that involves using their hands frequently, a smaller carat weight may be more practical and comfortable.
Budget: Ensuring that the carat weight youre aiming for is realistic for your budget, while still finding a balance between carat weight and the other 4 Cs is key to getting a beautiful ring without spending too much. One way to maximise the carat weight can be to select a lab-grown diamond rather than a ‘natural’ mined stone. For the latest diamond prices and market trends, refer to our dedicated pricing page.
Carat Weight and Diamond Shapes
Different diamond shapes look very different at the same carat weight.
In the example below, the 10 most common diamond shapes used in jewelry are compared to each other and a £1. These diamonds each weigh 5 carats (which is sizeable!), but the aim of the image is to show how large the differences between different shapes at the same carat weight can be.
Round diamonds and carat weight
The classic round shape is the most popular choice for engagement rings. The round diamonds’ symmetrical shape has been optimised to reflect as much light as possible in the form of sparkle, which means that they have to be a particular depth. This depth is deeper than some other shapes, which means that they are middle-of-the-pack when it comes to ‘facing up’ big.
Princess diamonds and carat weight
Princess cut diamonds are typically cut a little deeper than round cut diamonds, which means that they face up a little smaller.
Cushion diamonds and carat weight
Cushion cut diamonds are known for their soft, rounded edges and pillow-like shape, although there can be considerable variation in their shape. Some cushion cuts are square, while others are rectangular. It’s a good idea to check cushion cut sizes on a diamond-by-diamond basis, rather than just relying on the carat weight to gauge the diamonds size.
Oval diamonds and carat weight:
Oval-shaped diamonds are elongated and are cut more shallowly than many other diamons shapes, which can make them appear larger than other shapes at the same carat weight. Oval diamonds can therefore be a good choice for those who want a larger appearance without a significant increase in price.
Pear diamonds and carat weight:
Pear-shaped diamonds, also known as teardrop diamonds, are also elongated, so can also appear larger than their carat weight.
Marquise diamonds and carat weight:
While marquise cut diamonds aren’t the most common choice, they are the shape that looks the largest for a set carat weight.
Emerald diamonds and carat weight:
Emerald cut diamonds have a rectangular shape with step cuts, creating a unique and elegant appearance. Due to their large table (the flat top facet of the diamond), emerald cuts can show off their carat weight well, although they may not appear as brilliant as other shapes.
Asscher diamonds and carat weight:
Similar to the emerald cut, Asscher cut diamonds feature a square shape with step cuts. Asscher cut diamonds are typically cut to be deeper than other diamond shapes, which can mean that they ‘face up’ smaller when viewed from the top..
Radiant diamonds and carat weight
Radiant cut diamonds combine the brilliance of a round diamond with the modern shape of an emerald or Asscher cut. Like cushion cuts, there can be considerable variation in the shape of radiants – some are square, while others are rectangular – so it’s important to check the dimensions of any radiant you are considering.
Tips for Maximising the Appearance of Carat Weight
If you’re looking to make the most of your diamond’s carat weight, there are a few strategies you can employ to maximise its appearance:
- Choose a ‘fancy’ (non-round) shape with an elongated shape and a larger table e.g. oval, pear or emerald cuts.
- Choose a thinner band: A thinner band can make the centre diamond appear larger by comparison, drawing more attention to the stone.
- Choose a halo setting: A halo setting surrounds the centre diamond with a ring of smaller diamonds, creating the illusion of a larger stone while also increasing the ‘total carat weight’ (CTW) of the ring.
Diamond Certificates and Carat Weight
When purchasing a diamond, it’s crucial to ensure that it comes with a certification, or ‘grading report’ from a reputable entity. A diamond certification verifies the carat weight and other quality factors, such as cut, clarity, and colour.
Some of the most reputable certification grading labs include the Gemological Institute of America (GIA), the American Gem Society (AGS), and the European Gemological Laboratory (EGL).
Not only will a diamond certification provids an unbiased assessment of the diamond’s quality, it will also list out the diamond’s dimensions, allowing you to copare different diamonds of the same carat weight and ensuring you are comfortable with the size of the stone you are considering.
