A 1ct lab grown diamond engagement ring with an IGI certificate should cost between £900 and £1,900 in the UK in 2026, depending mainly on the gold it sits in. Pay much more and you are paying for a brand name. Pay much less and you should be asking what is missing, usually the certificate, the colour grade, or the gold itself.

I run THERESHEIS.jewels, an independent fine jewellery brand in Edinburgh. I price lab grown diamond rings for a living, and I compare wholesale and retail prices across the UK market every week. This is what the numbers actually look like right now.

How much is a 1ct lab grown diamond ring in the UK?

On the high street, 1ct lab grown rings sit roughly between £750 and £1,000. Look closely at those listings, though. Many are 14ct gold rather than 9ct or 18ct, and most do not state the diamond's colour or clarity anywhere on the page. You are buying a carat weight and a photo.

Hatton Garden jewellers and online specialists typically charge £1,000 to £1,500 for a certified 1ct solitaire, more in platinum.

At THERESHEIS.jewels, a 1ct round brilliant or oval solitaire in 9ct yellow gold is £925, and the same carat in 18ct gold is £1,795 to £1,850. Every stone is D/E colour, VS clarity, and IGI certified. Those letters matter more than the price tag, and I explain why below.

Does 9ct or 18ct gold change the price?

Yes, and it is the single biggest lever on the final number. The diamond can be identical. The gold decides whether you pay £925 or £1,795.

18ct gold contains 75% pure gold. It is richer in colour and it is the traditional choice for engagement rings. 9ct gold contains 37.5% pure gold, which makes it noticeably harder wearing and considerably less expensive. For a ring that never comes off, through washing up, gym sessions and gardening, 9ct is not the compromise people assume it is. It is the practical choice that happens to cost half as much.

If the diamond quality is stated and certified, choosing 9ct over 18ct is the cleanest way to put a full carat on your hand without crossing £1,000.

What does IGI certified actually mean?

IGI is the International Gemological Institute, an independent laboratory that grades diamonds. An IGI certificate states your diamond's exact carat weight, colour, clarity and cut. It is graded by people who have no interest in what the retailer charges you.

Two things to check on any listing. First, that the certificate is for your specific stone, not a general certificate of authenticity from the shop. IGI certified diamonds usually carry a laser inscribed number on the girdle of the stone that matches the certificate. Second, that you can verify it yourself. Enter the certificate number on the IGI website and the full grading report appears. If a seller cannot give you a number to check, that tells you something.

A note on grades, in plain terms. D/E colour means the diamond is at the very top of the colourless scale. VS clarity means any inclusions need a jeweller's loupe to find. Plenty of rings on the market are G-H colour and SI clarity, which still look white to the naked eye, but they should cost less. If a listing states no grades at all, assume the lower end and price accordingly.

Is a 2ct or 3ct lab grown diamond worth it?

This is where lab grown changes the conversation entirely. A 2ct oval solitaire in 9ct gold is £1,595 in my collection. Three carats is £1,995. Ten years ago those numbers bought you well under one carat of mined diamond.

One practical tip if size is the goal: choose an oval. An oval spreads its weight along the finger, so it wears visibly larger than a round of the same carat. My 2ct oval measures just over a centimetre long.

Why are lab grown diamonds getting cheaper?

Production has scaled, and prices have been falling by double digit percentages year on year. That trend is real and it is worth being honest about, because it changes how you should think about the purchase.

Buy a lab grown diamond for the piece, the moment, and the decade of wearing it. Do not buy it as a financial investment, and be sceptical of any seller who suggests otherwise. The upside of falling prices is entirely yours as a buyer: the same certificate, colour and clarity cost less every year, and sellers who bought stock expensively are the ones under pressure, not you.

What should you check before buying?

Ask five questions of any listing. Is the diamond certified by an independent lab such as IGI or GIA, with a number you can verify online? Are the colour and clarity stated, not just the carat weight? Is the metal solid gold, hallmarked, with the carat given? Is there a warranty, and what does it cover? And finally, does the price make sense against the numbers above for that gold and that carat?

If a ring passes all five, you are paying for diamond and gold. If it fails two or more, you are paying for marketing.

Frequently asked questions

How much does a 1 carat lab grown diamond ring cost in the UK? Between £900 and £1,900 for a certified stone in solid gold, depending on whether it is set in 9ct or 18ct. High street rings below this range often omit colour and clarity grades or use 14ct gold.

Are lab grown diamonds real diamonds? Yes. They are chemically and optically identical to mined diamonds and are graded on the same scale by the same laboratories. A jeweller cannot tell them apart by eye.

Is 9ct gold good enough for an engagement ring? Yes. 9ct gold is harder wearing than 18ct, which suits a ring worn every day, and it costs roughly half as much. The trade-off is a slightly paler colour and lower pure gold content.

How do I verify an IGI certificate? Enter the certificate number on the IGI website and the full grading report for that stone appears. Most IGI certified diamonds also carry a matching laser inscription on the girdle.

Do lab grown diamonds hold their value? No, and neither do most mined diamonds at retail. Prices for lab grown stones are falling as production scales. Buy the ring to wear it, not as an investment.

Every lab grown diamond at THERESHEIS.jewels is IGI certified, D/E colour and VS clarity, set in solid hallmarked gold, and covered by our 2 year warranty. The collection starts at £825 for a 1ct pendant and £925 for a 1ct engagement ring in 9ct gold. I am Patrycja, the founder, and if you have a question about a specific stone, write to me at hi@theresheisjewels.com.