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How Much Should You Pay for a Half Carat Diamond?

How Much Should You Pay for a Half Carat Diamond?

April 19 2024

If you’re looking to buy a half carat diamond – perhaps for an engagement ring – then working out what a 'good' price is can be a minefield. Diamond prices vary wildly and half carat diamond prices are no exception. So how are you supposed to set a reasonable budget?

In this article, we’ll take a look at some of the factors that affect how much half-carat diamonds cost, as well as explain how you can find the best value half-carat diamonds your money can buy.

Shop for half-carat loose natural diamonds

Shop for half-carat loose lab-grown diamonds

First, let’s get some pesky basics out of the way. Feel free to skip this bit if you already know about carats and what half of one is.

What exactly do we mean by half a carat?

A half-carat diamond weighs exactly 100mg (milligrams) – that is 1/10 of a gram.

You might have come across different ways of describing half a carat, such as:

  • half or ½ carat diamond
  • 0.5 or .5ct diamond
  • 50-point diamond (1 carat = 100 points)

All these terms mean the same thing.

How big is a half-carat diamond?

It varies. The carat weight of a diamond tells you very little about its size, as size depends more on the shape of the diamond and the way it’s been cut.

For example: Imagine two icebergs, both weighing 100,000 tonnes. One is tall and narrow, with most of its weight underwater. The other is wide, with a shallow base. Viewed from the top (as diamonds are), the first iceberg will look much smaller than the second.

The same size variation is true of diamonds (except diamonds generally support fewer penguins). This means it’s very difficult to ascertain a diamond’s size from its carat weight.

Even so, we can say with some confidence that a half-carat diamond will be between the following for each shape:

Diamond Shape Minimum Size Maximum Size Ideal Size
Round Brilliant 4.4 x 4.4mm 5.4 x 5.4mm 5.15 x 5.15mm
Princess 4 x 4mm 4.6 x 4.6mm 4.4 x 4.4mm
Emerald 5.3 x 3.5mm 6.3 x 3.5mm 5.5 x 4mm
Asscher 4.2 x 4.2mm 4.6 x 4.6mm 4.5 x 4.5mm
Marquise 7 x 4.1mm 8.5 x 4.1mm 8 x 4.1mm
Pear 6.3 x 4.3mm 7.8 x 4.3mm 7.3 x 4.3mm
Oval 6 x 4.3mm 7.2 x 4.3mm 6.7 x 4.3mm
Heart 5 x 4.3mm 5.5 x 5.3mm 5.4 x 4.8mm
Radiant 4.3 x 4mm 6.1 x 4mm 5.5 x 4mm
Cushion 4.2 x 4.2mm 4.6 x 4.6mm 4.4 x 4.4mm


Is a 0.5-carat diamond big enough for an engagement ring?

Yes, absolutely. It’s a very good size for engagement rings – not too big and not too small. Just right, as Goldilocks would say. A large proportion of diamond engagement rings are around the half-carat mark.

Hand-picked Half Carat Diamond Engagement Rings

Half-carat diamonds are also perfect for diamond earrings as the pair, together make a full-carat. (Kind of like “You complete me” for diamonds. Aaah.)

Now let’s move on to the question of half-carat diamond prices.

Q: How much does a ½ carat diamond cost?
A: Not half as much as a 1-carat diamond!

That’s truer than you think. It’s cheaper to buy two half-carat diamonds than it is to buy one 1-carat diamond. That’s because bigger rough diamonds are much harder to find and mine in the wild.

And, if you haven’t already guessed, there’s no such thing as a simple answer to the question of how much half-carat diamonds cost. Diamonds don’t come with RRPs. That’s because carat weight isn't the only factor determining the price. Quality is just as important, if not more. A 0.5-carat diamond with visible inclusions and a hint of colour will cost significantly less than one that’s flawless and colourless.

But you came here looking for a straight answer, so I'm going to try to provide one.

The ballpark answer:

A quick search of the 300,000+ natural diamonds listed on our website today (yes, that is a brag and no, it wasn't meant to be subtle) reveals that our least expensive 0.5-carat natural diamond costs £450 (a cheeky Emerald) and our most expensive 0.5-carat diamond costs £2,300 (a very Brilliant Round).

So, the answer to your question “How much does a half-carat diamond cost” is somewhere between £425 and £2,300 (On January 8th 2024).

That’s quite a price range. But it illustrates a point, which is that the price of a half-carat diamond can be whatever you want it to be.

Search for half-carat diamonds under £1500

A half-carat diamond for every pocket

The beauty of buying a diamond is that you never have to spend any more than you want to. That’s because each diamond is slightly different and they’re all arranged in an orderly fashion from least expensive to most. In fact, for any given budget there is a sparkling throng of potential diamond suitors vying for your attention, which gives you lots of delectable choices…

You might choose a diamond with the highest quality cut, or one that has excellent colour or clarity. Or you might focus on dimensions to get the biggest half-carat stone you can. (All of these things are not mutually exclusive, by the way.)

You could even choose a diamond that weighs less than half a carat…wait, what?

Oh yes, that’s the other important thing you need to know about diamond prices.

Why people who know about diamonds don’t buy half-carats

(Or 1 carat or 5 carats, for that matter.)

It’s a general rule that there’s more demand for diamonds that weigh exactly half a carat, one carat, or five carats. Because of this, those diamonds cost more (meaning you pay a higher price per carat).

Diamond experts know that if you drop the carat weight just a little – from 0.50 carats to 0.46 carats, for example – you can save quite a lot of money without losing anything in appearance.

Here are two virtually identical diamond volunteers to demonstrate:

Diamond A, aka “Felicia”
Round Brilliant
0.50 carats
F colour
VVS2 clarity
Certified by GIA
9.47 DiamondScore

Diamond B, aka “Priscilla”
Round Brilliant
0.45 carats
F colour
VVS2 clarity
Certified by GIA
9.50 DiamondScore

As you can see, these diamonds are very alike. Apart from a few very minor considerations, they are the same in all but carat weight. And in that, there’s just a four-point difference. Yet Felicia will cost you £635 more than Priscilla.

Or to put it another way, Priscilla’s price per carat is £2,033 (give or take a penny) and Felicia’s price per carat is £3,100!

With the advent of lab-grown diamonds, which are identical in chemical composition (yes, a real diamond), but made under extreme pressure and temperature, mimicking the process at the earth's mantle. You have another choice and a different price entirely!

Let's consider a third volunteer...

Diamond C, aka “Elvis”
Lab-Grown Round Brilliant
0.53 carats
F colour
VVS2 clarity
Certified by IGI
8.66 DiamondScore

Now granted, the DiamondScore isn't quite as high, but the benefit is a diamond for a third of the price... just £519 per carat! Definitely worth considering...

If you remember nothing else, remember this

  • There’s no such thing as a single price for half-carat diamonds
  • Price is based on quality as well as carat weight
  • Two half-carat diamonds will cost less than one 1-carat diamond
  • Save money by buying diamonds just below (or above) the half or whole-carat mark
  • Save even more money by considering a lab-grown diamond (or spend the money you save on a bigger diamond!)

Ultimately, carat weight should not be your only consideration. Yes, you may be able to get a cheap half-carat diamond but if it’s poor quality (which it probably is) then what you’re essentially buying is very expensive glass.

My advice is to use half a carat as your starting point, adjust your search to include diamonds that are 0.45 – 0.55 carats, and then use the Four C’s or our very handy DiamondScore to find the highest quality diamond that falls within your budget range.

And when you've done that, come back to tell me how much it cost :-)

Shop for half-carat loose natural diamonds

Shop for half-carat loose lab-grown diamonds

If you looking to have a half-carat diamond, whether it's natural or lab-grown, we can set it in your chosen jewellery or make an item of jewellery to your design. To find out more, click here.

We always have Diamond Experts on hand to answer any questions, so feel free to contact us here.

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