Diamond sizes
The 1 carat engagement ring
A 1 carat engagement ring is the picture many couples have in mind when they think of a proposal: a single, brightly sparkling diamond, big enough to be noticed at once and still delicate enough for every day. But how big is 1 carat really, and what does such a ring cost in Switzerland?
At émin you get a complete solitaire with a 1-carat lab-grown diamond in 18K gold or platinum, IGI-certified, from CHF 1'900. On this page we explain how big the stone looks on the finger, what matters for quality and when a natural diamond is worth it.
How big is 1 carat really?
Carat is a unit of weight: 1 carat equals 0.2 grams. On the finger, though, you don't see weight, you see the surface of the stone from above. A well-proportioned 1-carat round brilliant measures about 6.4 to 6.5 millimetres across, roughly the size of a pencil eraser seen from the top.
On an average ring finger such a stone covers about a third of the finger's width. It looks present and clear, but not showy. On a slender hand the same diamond looks bigger, on a stronger hand more subtle. That's why at our atelier you try several sizes on your own finger before you decide.
Worth knowing: two stones of exactly 1 carat can look different in size. If a diamond is cut too deep, a lot of weight sits in the lower part nobody sees, and the visible surface stays smaller. A well-cut stone shows you the full face.
1 carat by cut: how big the stone looks
Same weight, different shape: elongated cuts spread the carat over more surface and therefore look bigger than a round brilliant.
| Cut | Dimensions at 1 carat (approx.) | Look on the finger |
|---|---|---|
| Round (brilliant) | approx. 6.4 to 6.5 mm | The classic, maximum sparkle, timeless |
| Oval | approx. 7.7 × 5.7 mm | Looks bigger than round, lengthens the finger |
| Princess | approx. 5.5 × 5.5 mm | Square, modern, looks rather compact |
| Cushion | approx. 6.0 × 6.0 mm | Soft corners, romantic, lots of fire |
| Emerald | approx. 7.0 × 5.0 mm | Step cut, calm and elegant, shows clarity clearly |
| Pear | approx. 8.5 × 5.5 mm | Elongated and soft, looks noticeably bigger |
| Marquise | approx. 10.0 × 5.0 mm | Biggest look per carat, very striking |
Guide values for common proportions. Every stone varies slightly with its cut, the exact dimensions are on the certificate.
Lab-grown or natural at 1 carat
A lab-grown diamond is a real diamond: the same hardness, the same chemical composition, the same sparkle. It forms in a few weeks in a lab instead of over millions of years in the earth. To the naked eye, and even under a loupe, there is no visible difference. It can only be identified with specialist lab equipment.
The difference is the price. A natural 1-carat diamond in good colour and clarity quickly runs to five figures. Our Heritage line with a GIA-certified natural diamond from 1 carat starts at CHF 6'500, but depending on quality the stone can be well above that. With a lab-grown diamond you get the same size and very good quality for a fraction of the cost.
Which choice is right depends on you. For some, the story of a stone from the earth matters, for others a large, flawless diamond at a fair price. We show you both side by side and talk openly about the pros and cons, resale value included.
Which of the 4Cs really count at 1 carat
The 4Cs are carat (weight), cut, colour and clarity. At 1 carat the stone is big enough for differences to show. This is how we set priorities:
Cut first
The cut decides how much light the diamond returns. At 1 carat we recommend the top cut grade (Excellent or Ideal). A mediocre cut looks dull, no matter how good the colour and clarity are.
Colour D to H
Colour describes how colourless a stone is, from D (completely colourless) to Z. In white gold or platinum, G and H still look clearly white at 1 carat. In yellow or rose gold you can even go a little lower.
Eye-clean clarity
Clarity measures tiny inclusions. From VS2 they are practically never visible to the naked eye at 1 carat. You don't need more than eye-clean, because VVS looks no different on the finger.
Certificate
Every stone comes with a certificate from an independent lab: IGI (International Gemological Institute) for lab-grown diamonds, GIA (Gemological Institute of America) for natural ones. It lists all 4Cs and the exact dimensions.
What a 1-carat diamond costs
The price of a 1-carat diamond depends first on whether it was grown in a lab or formed in the earth, and only then on colour, clarity and cut. Instead of showing you a table of average prices that won't match your stone anyway, we'd rather tell you what you concretely get with us.
Our Essential line is made for exactly this: a complete engagement ring with a 1-carat round brilliant lab-grown diamond, classic prong setting, 18K gold or platinum and an IGI certificate, from CHF 1'900. Not a loose stone with a surcharge for the setting, but the finished ring, made to your ring size.
If you'd like a different cut, a special setting or a natural diamond, we work out the price openly with you, item by item, before you decide.
Prices for a 1 carat engagement ring
Guide values for orientation. We discuss the exact price for your ring in person.
Price depends on the work involved. We calculate openly, no surprises.
Guide values, as of 2026, including VAT. For natural diamonds the price depends heavily on colour and clarity.
Designs for your 1-carat diamond
Every design in our collection can be made with a 1-carat stone, in the shape and metal of your choice.
Frequently asked questions
A well-proportioned 1-carat round brilliant measures about 6.4 to 6.5 millimetres across. Oval, pear and marquise cuts are longer and look bigger at the same weight, a princess cut rather more compact. The exact dimensions of your stone are always stated on the certificate.
At émin you get the complete ring with a 1-carat lab-grown diamond, 18K gold or platinum and an IGI certificate from CHF 1'900. With a natural diamond our Heritage line starts at CHF 6'500, although a natural one-carat stone of good quality quickly reaches five figures. We work out the exact price openly with you.
For most hands 1 carat is a very balanced size: clearly visible but practical for everyday wear. On slender fingers the stone looks bigger, on stronger hands more subtle. It's best to try different sizes at the atelier, the feeling on your own finger often decides faster than any chart.
No, neither with the naked eye nor under a loupe. Both are chemically real diamonds with the same hardness and the same sparkle. They can only be told apart with specialised lab equipment. The difference lies in origin and price, not in how the ring looks on your hand.
In white gold or platinum we recommend colour D to H, in yellow or rose gold it can be a little warmer. For clarity, VS2 or better is enough, then inclusions are invisible to the naked eye. Never save on the cut, because it decides how much the stone sparkles.
With natural diamonds often yes: round marks like 1 carat are in higher demand, and a stone just below looks almost the same on the finger but costs noticeably less. With lab-grown diamonds this jump is much smaller, which is why our Essential ring is deliberately priced with a full 1 carat.
IGI (International Gemological Institute) and GIA (Gemological Institute of America) are independent labs that measure and grade a diamond. The certificate records carat, colour, clarity, cut and the exact dimensions. So you know in black and white what you are buying. With us every stone comes with a certificate.
Quick enquiry
Your 1 carat engagement ring
Tell us briefly which shape and metal you like. We'll show you suitable stones and get back to you within one working day, happily with an appointment at the atelier or by video.