Jewellery Guides

One Carat Diamond Ring Buying Guide

Written by Sarah-Jane Santos
October 16th, 2020 • 6 min read

How big is a one carat diamond? - Can I afford one?

And how does the price of a one carat diamond compare to something a little smaller? How can I buy a one carat diamond for my engagement ring with a tight budget? Fear not: our gemmologists lay it all out, in our complete guide to one carat diamonds.

Firstly, what is a ‘Carat’?

Each and every diamond is graded for a number of characteristics that reflect the beauty, rarity and value of the stone. These characteristics are known as the 4Cs: cut, colour, clarity, and carat. ‘Carat’ is a measurement of a diamond’s weight. Generally speaking, the heavier the carat weight, the larger the diamond will appear.

Historically, diamonds were measured in relation to the number of carob seeds that equated to the same weight; a one carat diamond and a typical carob seed each equate to 0.20 grams. The metric has since evolved to become the highly accurate measurement now known as ‘carat’ weight, that is measured and recorded by diamond grading laboratories like the GIA.

How much does a one carat diamond ring cost?

There are a number of variables, other than carat weight, that can determine a diamond’s value. A one carat natural diamond with the optimum grades or beauty and value for money could cost between £6,200 and £9,000 - or around £1,800 for a lab diamond. If you were to compromise greatly on the cut, clarity and colour grade of a natural one carat diamond, you could find options as low as £4,000. This, however, would directly impact the beauty of the stone; finding the right balance between the quality of the 4Cs is crucial for finding a diamond with brilliance, sparkle and lustre.

Diamond Carat Weight Natural Diamond Lab Diamond
0.50ct £1,500 to £1,750 £900 to £1,200
0.75ct £3,000 to £3,200 £1,200 to £1,400
0.90ct £5,000 to £7,500 £1,500 to £1,800
1.00ct £6,200 to £9,000 £1,800 to £1,900
1.50ct £12,000 to £16,000 £3,000 to £3,500
2.00ct £24,000 to £28,000 £3,600 to £6,000

When budgeting for your engagement ring, consider the costs of the various ring designs that interest you. The more simple the design, the more budget you can dedicate to the centre diamond of your ring! Here are some typical prices for different ring design styles, before the cost of the centre diamond is added:

Solitaire settings cost £700

Halo settings cost from £1,600 to £2,250

Diamond band settings cost from £1,300 to £1,500

Trilogy settings cost from £900 to £1,950

How big is a one carat diamond?

Technically speaking, not all one carat diamonds will appear the same size. ‘Carat’ is a measurement of weight, rather than size, equating to 0.20 grams. A well cut, round brilliant diamond could look a totally different size to a poorly cut diamond with the exact same carat weight. Learn about cut grades and how this can affect the size your diamond appears.

Diamond shape can greatly affect how big it appears; elongated shapes, such as pear or oval diamonds can look larger than round diamonds of the same carat weight. So when it comes to questioning how big a one carat diamond is, there’s no one, straight answer.

Here’s how big one carat diamonds of different shapes appear when viewed from above:

Graph showing which 1ct diamond shapes appear the largest

Can you tell a 1ct diamond and 0.90ct diamond apart?

The visible difference between a 1ct diamond and a 0.90ct diamond is minimal - but the price difference can be significant. Many engagement ring buyers will prefer to dedicate their budget to a really good quality, beautiful diamond between 0.90ct to 0.99ct, rather than aiming to hit the 1ct but compromising on the quality of the stone.

Remember, the cut quality of the diamond has the largest impact on the stone's beauty, closely followed by the colour grade. A slightly smaller, but a brighter, whiter and sparklier diamond will likely give you more joy than a larger stone that's dim, dull or yellow in tone.

These two photos show the same diamond ring. We’ve manipulated one of the images to make the stone slightly larger. One image reflects the size of a 0.90ct diamond, and the other a 1ct diamond. How noticeable is the 0.10ct difference to you?

Can you tell which is 1ct?

Discover styles you love, with our gallery of custom rings.

How to find the best value one carat diamond

Keep the following grade ranges in mind:

  • Triple Excellent cut or XXX - meaning Excellent cut, Excellent polish, and Excellent symmetry, or at the very least Very Good. Only round diamonds receive a cut grade, so look at polish and symmetry for other diamond shapes.
  • D to F colour, or down to G or H if choosing a yellow gold ring
  • VS2 to SI1 clarity, or slightly higher for step cut diamonds, like emerald cuts

These grade boundaries will find you the most aesthetically beautiful diamonds - bright and rich in brilliance, whilst ensuring value for your money. Don’t get caught out by qualities that sound great, but in reality will cost you more for negligible benefit: for example, a higher clarity grade than VS2 will cost more money but will not be noticeable to the naked eye.

Connect with a Queensmith gemmologist. Let them know your rough budget, and they’ll prepare a selection of the best diamonds or gemstones for your ring ahead of your appointment. No complex decisions, just great value for money.

What if I can’t afford one carat diamond for my ring?

You shouldn’t put too much pressure on buying a one carat diamond; the reality is that the average diamond size for UK engagement ring buyers is 0.60ct - a still very sizeable carat weight that will make for a beautiful engagement ring. If, however, you’re super keen on hitting the one carat mark without spending beyond your means, why not consider alternatives to natural diamonds?

Gemstones like sapphires, rubies and emeralds retail at a significantly lower cost than diamonds.

Lab grown diamonds can cost around 40-60% less than a natural, mined diamond. Unlike diamond simulants like moissanites, lab diamonds are considered 100% real diamonds, and are visually and physically identical to natural diamonds, so are a great way to ensure a large diamond at an exceptionally reasonable price.

Finding a One Carat Diamond with Hatton Garden Jewellers

If you’d like a little more information, know exactly what you want, or would like to hear from the experts, we’re here to help - just drop us a message.

At Queensmith, each of our consultants are trained gemmologists, with the expertise and passion to find each client the perfect diamond for them, and their engagement ring. Whether you’re looking for a one carat diamond, or want to know a little more about budgeting and what you can find for your money, our gemmologists are on hand to help. Contact us to learn more or book an appointment.


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