Diamond Carat Weight

You can’t always tell the diamond’s size based on carats which is the measure of a diamond’s weight. Carats affect the way diamonds are priced, and the number changes exponentially. In this article, we explain the difference that even 0.1 carat can make.


A 0.1 Carat Diamond Size

The term carat (ct) is used to refer to the weight of a diamond. Broken down, one carat equals 200 milligrams (0.20 grams) and is divided into 100 points for precision. A diamond weighing one-tenth of a carat (ct) may be referred to as 0.10 carats or “10-points.”

The weight of the diamond is just one of the determining factors when it comes to the stone’s beauty, overall look, and worth. Carat weight is just one of the essential 4cs (carat weight, color, cut, and clarity) of diamond appraisal to determine the diamond quality.

Contrary to popular opinion, a diamond’s carat weight is not necessarily reflective of its actual size. Two diamonds of equal carat weight may appear slightly different in mm size when viewed from above depending on their other attributes.

When evaluating the mm (millimeter) size of a diamond, the top diameter and cut grade of the stone is taken into account along with carat weight. Together these are known as diamond dimensions. The distance across the top of the diamond is crucial, as this is how diamonds are generally viewed once set in jewelry. The cut (giving the diamond shape) similarly affects the stone’s perceived size. A well-proportioned diamond maximizes light performance, making it appear a larger jewelry piece.

Diamond prices tend to jump by half-carats, more than a slight difference You will find that the price difference between a 0.9 and 1.00 ct. weight diamond (or 0.75 ct and 0.50 ct) is much larger than the difference between a 0.8 and 0.9 ct (or 1.25 ct /1.50 ct) weight diamond. Furthermore, diamond prices increase exponentially, rather than linearly. The scarcity of large gem-quality rough diamonds means that a single good cut 2.00 ct stone will cost much more than two one ct diamonds. Also, it’s not guaranteed that two diamonds of the same carat weight, i.e., equal carat weight are going to be valued at the same amount. There are other factors involved too.

TIP: “Carat” (abbreviated ct) is not the same as “karat” (abbreviated K or kt). Although both are jewelry units of measure, Carat is a measure of gemstone weight while karat is a measure of gold purity.


This carat weight diamond size chart describes the carat weight of a diamond and its width in millimeters (mm size) This diamond size chart gives you an idea of the ratio of carat weights to a diamond’s physical (mm) size.

Diamond Sizes

Frequently Asked Questions About Diamond Carat Weight

A single carat is 0.2 grams, and a 1-ct diamond jewelry will normally have a diameter of approximately 6.5 mm. The size of a diamond’s diameter (mm) does not increase proportionately with the number of carats.
Prices for half-carat diamonds start at approximately $700 and can rise massively depending on the cut, color, and clarity of the diamond. The most you be likely to pay for the stone alone is about $2,000.
A 1 carat round diamond should measure around 6.5 mm.
There are a lot of factors to take into account which will determine the value of a 0.1-carat diamond price (or a 0.10-carat diamond price), including the cut, clarity, color, and shape of the stone. Prices currently vary from anything from $1,800 to in excess of $12,000.
A 5-carat diamond weighs approximately 1.0 gram. 
8-Carat diamonds are scarce and prized. You can expect its buying price to be between $12,500 to $40,000 per carat for diamonds of this (millimeter) size if ever you come across them.
The price of diamonds increases as carat weight increases. The Regent Diamond owned by the French state, on display in the Louvre, has a carat weight of 140.64 (28.128 g) is worth $73,920,000 USD. It is considered the most beautiful and purest diamond in the world.
“Carat” (ct) is not the same as “karat” (K or kt). Carat is a measure of gemstone weight such as diamond carat size, while karat is a measure of gold purity. Both are used in the measurement of jewelry.
Engagement rings vary enormously in cost, even if you limit your choice among the popular round cut diamonds so it is impossible to give a fixed cost. There are several diamond experts who believe that the man should spend two months’ salary on an engagement ring, while others argue it should be just a month. Probably the best option is to choose an engagement ring that looks good on your partner’s hand and she will cherish it forever and that fits within your budget.
Most insurance companies will insure these rings as they would other jewelry. However, as they have far more worth than merely monetary value, accurately putting a price on the ring can be a bone of conjecture. Some insurers say that the current market value plus twenty-five percent is accurate, while others say significantly higher or frustratingly lower.
The Hope diamond was removed from its setting in 1974 and was found to weigh 45.52 carats, significantly more than the 44.5 carats which it was previously valued at. It is known as an l lb diamond and is semi-conductive and phosphoresce.
Here are the ten most expensive, costliest diamonds in the world, according to clarity, sparkle, measurement, ct weight:
The Maoussaieff Red Diamond, discovered in Brazil in 199os, formerly known as the Red Shield and the largest red-colored diamond. With a triangular brilliant-cut and weighing 5.11 ct, displayed at the Smithsonian Institution in 2003 and 2005 as one of the most incredible diamonds in the world. This triangular cut diamond is estimated at $8 Million.
The Heart of Eternity, vivid blue fancy diamond mined in South Africa. Originally 77 ct rough diamond then cut into heart-shaped, exceptionally rare for lack of gray or black undertones, priced at $16 Million.
The Perfect Pink, intense pink 14.23 ct emerald-cut diamond, sold for $23.2 at Christie’s Auction in 2010.
The Wittelsbach Diamond, originally 35.56 ct then recut in 2010 to 31.06 ct, fancy deep blue internally flawless and part of Spanish and German Royalty since arrival in Europe in the 1600s. The recut was controversial but it rendered the stone now deep blue and internally flawless, priced 15 $23.4 Million.
The Winston Blue, originally called the Fancy Vivid Blue Diamond, was renamed after its purchaser Harry Winston in 2014. This pear-shaped internally flawless diamond cost $23.8 Million, almost $2 Million/carat, setting a new world record for a blue diamond color.
The Pink Star, which was mined in South Africa, originally known as Steinmetz Pink, is the world’s largest diamond graded as fancy vivid pink color. Bought in Sotheby’s Auction 2017 over a telephone bid for $71.2 Million, this internally flawless 59.60 ct oval-shaped was then renamed CTF Pink Star for the buyer’s late father.
The Centenary Diamond, 100 ct in its rough form, later 273.85 ct after its recut (for 154 days) to heart shape which improved the color and clarity grade to flawless. It is priced at $71.2 Million.
The Hope Diamond, priced at $200- $250 Million, the45.52 ct fancy dark gray-blue color antique cushion cut diamond was believed to have been discovered in India in the 1600s then bought by King Louise XIV in 1668. Stolen on a 1791 Crown Jewel Looting, later resurfacing in London in 1839. Purchased in 1949 by Harry Winston and donated to the Smithsonian Institution. Rumors until the present of being cursed due to the ill fate met by previous owners.
The Cullinan, also known as the Star of Africa, up to $2 Billion, the largest rough diamond of gem quality ever found. At 3,106.75 ct, discovered in Cullinan, South Africa in 1905 and gifted to King Edward VII, was then cut into 9 main stones, the largest at 530.2 ct is called Cullinan I.
The Koh-I-Noor, at 105.6 ct, the colorless oval-shaped gem found in India in the 1300s is full of mystery and legend. Additionally, it is also called Mountain of LIght and Diamond of Babur. Said to rightfully belong to India and was just stolen by England in 1850. Cut by order of Prince Albert from 186 ct to 105.6 ct to increase brilliance and sparkle characteristics.
There is no one perfect carat weight. You need to consider all the different factors when purchasing diamonds.
Carat weight is not necessarily reflective of a diamond’s size. Two diamonds of equal carat weight may look different in size depending on their other attributes. It’s also important to consider the stone’s cut grade and top diameter as these can make it look bigger or smaller. Together these are known as the diamond’s dimensions and will determine the diamond’s size. You can confirm this in a diamond size chart.
There is no standard weight for diamonds. One carat is essentially equal to 0.200 grams or 1/5 gram and is further subdivided into 100 points. A stone weighing one-tenth of a carat (ct) may be referred to as 0.10 carats or “10-points”.
A carat is equivalent to 200 milligrams, meaning one carat is 100 ‘points.’ This is to allow the measurement to be as precise up to the hundredth decimal place. To a jeweler, a diamond that weighs below one crat is measured by its ‘points’ value alone.
To know how real a diamond is, look at it through a magnifying glass and try to find imperfections in the stone. If no imperfections are visible, the diamond is fake, not real. Real diamonds have imperfections, called inclusions.
If you are in a shop, you can ask to see the diamond certificate – it is the assurance of the quality and values of the stone and is its proof of “identity” to save you a considerable amount of time.
The popular range of weights for engagement rings is from 1.0 -1.9 carats. Peaks are observed at 0.7-0.79 (averaging at 0.75 ct), 0.90-0.99 and 1.50 – 1.59 ranges. In the United States, the average is 1. carat, in the UK it is 0.6 carats, in Europe, it’s around 0.50 ct. If you want to splurge or show off, you could try going for 2.00 ct.
There is no ideal carat weight, the ideal proportions, weights and settings are up to your preference or effect you would want on your fiancee. You can also choose what would be a good match to her hand or finger. You could ask your jeweler for settings advice or consult a carat weight chart (table) or a diamond carat guide to help you decide before buying.
The popular diamond cuts and shapes are:
round diamond/round brilliant cut (the round diamond or round cut is the most “popular” cut for engagement rings
princess (or square) cut
emerald cut
cushion cut
radiant cut
asscher cut
pear cut
oval cut
heart shape
marquise cut
There are other cuts that aren’t often seen and which are patented to specific brands. For example, the asprey, eighty-eight, ashoka, jubilee, crisscut, lily cut, princess plus cut, royal asscher cut, bead cut. These shapes come in different ct sizes, diamonds and other stones.