Display currency
Estimated display prices. Checkout is charged in USD.
Welcome offer
10% off your first order
Create a free Ronora account with Google or your email to unlock it. No password needed.
Your welcome offer is ready. Apply it now and the saving shows at checkout.
WELCOME10 is applied. You save .
We could not apply the offer to this cart. If you think this is a mistake, please contact us.
What do you know about
diamonds
Explore the captivating world of diamonds. Learn about their origin, beauty, and the 4 Cs that define their quality. Welcome to the world of timeless elegance and enduring brilliance.
By Fiona, founder of Ronora Diamond. Updated September 26, 2026.
A 1 carat round diamond pendant measures about 6.5 mm across, a little over a quarter of an inch, and a 2 carat round about 8.2 mm. Hung vertically, a 1 carat pear is about 7.9 × 5.3 mm and a 1 carat oval 7.7 × 5.7 mm, so elongated shapes look taller on the neck for the same weight. Chain length decides where the stone sits: a 16 inch chain at the base of the neck, an 18 inch chain just below the collarbone and a 20 inch chain at the top of the neckline. The bail that holds the chain adds a few millimeters above the stone.
Choose Pendant, pick a shape and set the carat weight. The stone is drawn on a chain at the neckline at true scale, hung vertically or horizontally. Switch to millimeters if you already know the size you want, and calibrate once against a bank card so the drawing matches real life on your screen.
Measure the longest axis and the widest axis of the face-up outline. Carat weight is estimated from those two figures and the proportions this shape is normally cut to.
A 1.00 ct round measures
6.50 × 6.50 mm
Drawn at true physical size once your screen is calibrated. Hold a ring up to the outline to judge it properly.
Hold any bank card against the bar below and drag the slider until the two match exactly. A standard card is 85.6 mm wide. Your setting is remembered on this device.
Same weight, twelve outlines. The bars are drawn to scale against each other, longest first.
Millimeter figures are for well proportioned stones cut to the ratio shown. Individual stones vary, so ask us for the exact measurements on any stone before you order. The Dutch Marquise is one of our own cuts and has no published trade chart; those figures are Ronora's working sizes.
Face-up size of the stone in millimeters, by carat weight. The bail adds a few millimeters above the stone.
| Carat | Round (mm) | Cushion (mm) | Heart (mm) |
|---|---|---|---|
| 0.25 ct | 4.1 × 4.1 | 3.5 × 3.5 | 4.1 × 4.1 |
| 0.50 ct | 5.2 × 5.2 | 4.4 × 4.4 | 5.2 × 5.2 |
| 0.75 ct | 5.9 × 5.9 | 5.0 × 5.0 | 5.9 × 5.9 |
| 1.00 ct | 6.5 × 6.5 | 5.5 × 5.5 | 6.5 × 6.5 |
| 1.50 ct | 7.4 × 7.4 | 6.3 × 6.3 | 7.4 × 7.4 |
| 2.00 ct | 8.2 × 8.2 | 6.9 × 6.9 | 8.2 × 8.2 |
| 2.50 ct | 8.8 × 8.8 | 7.5 × 7.5 | 8.8 × 8.8 |
| 3.00 ct | 9.4 × 9.4 | 7.9 × 7.9 | 9.4 × 9.4 |
| 4.00 ct | 10.3 × 10.3 | 8.7 × 8.7 | 10.3 × 10.3 |
| 5.00 ct | 11.1 × 11.1 | 9.4 × 9.4 | 11.1 × 11.1 |
Round and heart share the same size at each weight in our proportions, and the cushion is more compact because it carries more weight in depth. See a 1 carat round pendant on the neckline.
Height by width in millimeters for elongated pendant stones hung vertically. Hung horizontally, the two numbers swap.
| Carat | Oval (mm) | Pear (mm) | Emerald (mm) |
|---|---|---|---|
| 0.25 ct | 4.8 × 3.6 | 5.0 × 3.3 | 4.4 × 3.1 |
| 0.50 ct | 6.1 × 4.5 | 6.3 × 4.2 | 5.6 × 4.0 |
| 0.75 ct | 7.0 × 5.2 | 7.2 × 4.8 | 6.4 × 4.5 |
| 1.00 ct | 7.7 × 5.7 | 7.9 × 5.3 | 7.0 × 5.0 |
| 1.50 ct | 8.8 × 6.5 | 9.1 × 6.1 | 8.0 × 5.7 |
| 2.00 ct | 9.7 × 7.2 | 10.0 × 6.7 | 8.8 × 6.3 |
| 2.50 ct | 10.4 × 7.7 | 10.8 × 7.2 | 9.5 × 6.8 |
| 3.00 ct | 11.1 × 8.2 | 11.5 × 7.6 | 10.1 × 7.2 |
| 4.00 ct | 12.2 × 9.0 | 12.6 × 8.4 | 11.1 × 7.9 |
| 5.00 ct | 13.2 × 9.7 | 13.6 × 9.1 | 12.0 × 8.5 |
Elongated shapes look taller than a round of the same weight. Open a 1 carat pear pendant in Find Me Diamond to see the drop at actual size.
Necklace length is the full chain including the clasp.
| Chain length | Where it sits | Worth knowing |
|---|---|---|
| 16 inch | At the base of the neck | Keeps a small pendant close to the face |
| 18 inch | Just below the collarbone | Frames the collarbone, an easy first length |
| 20 inch | At the top of the neckline | Gives a larger stone room to hang |
Every neck is different, so try a length with a piece of string before you order.
Start with how you want the pendant to read. A small stone of 0.25 to 0.5 carat, 4.1 to 5.2 mm across in a round, gives a delicate point of light that works every day and layers easily with other chains. A 1 carat stone at 6.5 mm reads as a solitaire rather than an accent at conversation distance. From 2 carats, 8.2 mm and up, the pendant becomes the focus of the neckline.
Think about what you usually wear. A pendant sitting on bare skin at an open neckline shows its full size, while one lying on fabric has more competition around it and needs a little more presence to stand out.
If you are deciding between two weights, compare them in the calculator on this page, for example a 1 carat round pendant against a 1 carat pear. Then check the neckline in a mirror with your phone held at the collarbone, after calibrating the calculator against a bank card so the drawing is true to size.
Chain length changes the look almost as much as the stone does. We measure necklace length as the full chain including the clasp. A 16 inch chain sits at the base of the neck, an 18 inch chain just below the collarbone, and a 20 inch chain at the top of the neckline.
A shorter chain keeps the stone close to the face, where it is seen together with your earrings, and it suits a small stone that might otherwise get lost. A longer chain lets the pendant fall where there is more open space around it, which gives a larger stone room to hang.
Match the chain to the neckline you wear most. The pendant should sit where your skin or the neckline frames it, not where a seam cuts across it. The simplest check is a piece of string: tie it at 16, 18 and 20 inches, hang a ring on it as a stand-in, and look in a mirror. Our size guide explains how we measure every length.
Hung vertically, elongated shapes measure tallest for their weight. At 1 carat, a pear is 7.9 × 5.3 mm, an oval 7.7 × 5.7 mm and an emerald cut 7.0 × 5.0 mm, against 6.5 mm for a round. A heart of the same weight is 6.5 × 6.5 mm, and a cushion 5.5 × 5.5 mm, the most compact of the six.
Height matters on the neck because a pendant is seen hanging, and the eye reads the drop. The pear is the classic teardrop and the tallest shape here; the oval is softer and a little shorter. An emerald cut shows long, mirror-like flashes rather than sparkle, and its straight lines echo the line of a chain. A heart reads most clearly as a heart when the stone is large enough for its cleft to show, so it is worth checking at actual size.
Any shape can also hang horizontally, east-west. The calculator switches between vertical and horizontal, so you can see an oval pendant hung sideways next to the classic vertical drop.
The stone is only part of the pendant. The bail, the loop the chain passes through, adds a few millimeters above the stone, and the setting adds a frame of metal around it. A three or four prong solitaire keeps that frame light, so the diamond does most of the talking. A bezel wraps the stone in a thin rim of metal and makes it read slightly larger and softer. A halo of small diamonds turns the center stone and its frame into one larger shape of light.
This is why pendant size charts give the stone size, not the size of the finished piece. When you compare pendants from different jewelers, compare the center stone in millimeters first, then look at how much metal and how many accent stones surround it.
The charts on this page are stone sizes only. The calculator shows the stone on a chain at the neckline, so you can judge the diamond itself before thinking about the setting around it.
Every size on this page is the face-up size of the center stone, height by width in millimeters, for a well proportioned stone cut to the classic ratio of its shape. For elongated shapes hung vertically, the first number is the height. Chain length is measured separately, as the full chain including the clasp.
Individual stones vary by a few tenths of a millimeter with cut depth, so two pendants of the same weight can measure slightly differently. Ask us for the exact measurements of a specific stone before you order, or send us the height you want and we will tell you the carat weight that gives it.
Every Ronora diamond is a real CVD lab grown diamond, Excellent cut, D-E-F colorless with VVS clarity, made to order in Surat. See our lab grown diamond pendants, and read the diamond shapes guide for how each shape carries light.
A 1 carat round diamond pendant is about 6.5 mm across, a little over a quarter of an inch, with the bail adding a few millimeters above it. A 1 carat pear hung vertically is about 7.9 × 5.3 mm and a 1 carat oval 7.7 × 5.7 mm. On an 18 inch chain the stone sits just below the collarbone, where it reads clearly as a solitaire.
Between 0.5 and 1 carat, 5.2 to 6.5 mm across in a round, is the easiest range for everyday wear. Under 0.5 carat the pendant is a delicate accent that layers well; from 2 carats, 8.2 mm and up, it becomes a statement. There is no correct weight, so compare two sizes at actual size before you choose.
Yes: at about 6.5 mm across, a 1 carat round is large enough to read as a solitaire at conversation distance and still easy to wear every day. If you want more height for the same weight, a 1 carat pear at 7.9 × 5.3 mm or an oval at 7.7 × 5.7 mm looks taller on the neck.
A 2 carat round pendant is about 8.2 mm across, only about 26% wider than a 1 carat round at 6.5 mm, because size grows with the cube root of weight. Hung vertically, a 2 carat pear is about 10.0 × 6.7 mm and a 2 carat oval 9.7 × 7.2 mm. At this size the pendant becomes the focus of the neckline.
An 18 inch chain places the pendant just below the collarbone and a 20 inch chain at the top of the neckline, so the better one depends on what you wear. Choose 18 inches for open necklines and everyday wear with the stone on skin. Choose 20 inches to wear the pendant over a higher neckline, or to give a larger stone more room to hang.
A 16 inch chain sits at the base of the neck and an 18 inch chain just below the collarbone. The 16 inch length keeps a small pendant close to the face and suits open collars; the 18 inch length lets the stone rest along the collarbone. Try both with a piece of string before choosing, since the same chain sits differently on every neck.
A 1 carat oval on a pendant size chart reads 7.7 × 5.7 mm: that is the stone's face-up height by width, not the size of the finished piece. The bail and the setting add a little around the stone, and chain length is measured separately in inches. Compare pendants by the center stone first, then by the setting.
Of the pendant shapes on this page, a pear hung vertically measures tallest: a 1 carat pear is about 7.9 × 5.3 mm, against 6.5 mm for a round. The oval (7.7 × 5.7 mm) and emerald cut (7.0 × 5.0 mm) also measure taller than a round of the same weight, while a cushion is the most compact at 5.5 × 5.5 mm.
A 0.5 carat round pendant is about 5.2 mm across, and a 0.5 carat pear hung vertically about 6.3 × 4.2 mm. That is a delicate size that catches the light without drawing attention to itself, and it layers well with other chains. On a 16 inch chain it sits at the base of the neck, close to the face.
Yes: on a 1 carat round of 6.5 mm, the bail adds a few millimeters above the stone, so the finished pendant looks taller than the stone alone. A heavier bail or a halo makes the whole piece read larger. When you compare pendants, compare the center stone in millimeters first, then look at the setting around it.
Lab grown diamond pendants and necklaces
