Understanding Diamond Carat Weight The term carat (ct) is used to describe the weight of a diamond. To break it down, one carat equals 200 milligrams (0.20 grams), which is divided into 100 points for precision. Therefore, a diamond weighing one-tenth of a carat may be referred to as 0.10 carats or “10-points”. It is important to note that “carat” (abbreviated ct), in this case, is not the same as “karat” (abbreviated K or kt). Although both are units of measurement used in jewelry, carat is a measure of gemstone weight, while karat is a measure of gold purity. Diamond carat weight is just one determining factor in a stone’s overall appearance and worth. The other factors include color, clarity, and cut. Together, they constitute the “4Cs” of diamond appraisal, which experts use to evaluate diamond quality. You can click here for more information on the 4Cs from our affiliate website, James Allen. Understanding Diamond Size Contrary to popular belief, a diamond’s carat weight does not necessarily reflect its actual size. For example, 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 millimeter (mm) size of a diamond, the stone’s cut grade, diameter (i.e., its shape as viewed from the top), and carat weight are taken into account. Together, these are known as the diamond’s dimensions. The distance across the top of the diamond is crucial since this is how diamonds are generally viewed once set in jewelry. The cut similarly affects the stone’s perceived size. A well-cut diamond maximizes light performance (or sparkle), making it appear larger in a jewelry piece. A Note on Diamond Market Retail Price Diamond prices tend to jump by half-carats, making more than a slight difference. Thus, you will often find that the price difference between a 0.9 and 1.00 ct 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 and 1.50 ct) diamond. Furthermore, diamond prices increase exponentially rather than linearly. For instance, the scarcity of large gem-quality rough diamonds means that a single good cut 2.00 ct stone will cost much more than two 1.00 ct diamonds. It is also not guaranteed that two diamonds of the same carat weight (i.e., equal carat weight) will be valued at the same amount. There are other factors involved, too. Weight & Carat Diamond Size Chart This carat weight and diamond size chart describes the carat weight of a diamond along with its width in millimeters. This will give you an idea of the ratio of the different carat weights to a diamond’s physical (mm) size. How is Diamond Weight Measured? Measuring the weight of a diamond can be straightforward when you have the right tools, but it can also be tricky, especially when the diamond is set in jewelry. Below, we provide an overview of the tools, methods, and challenges involved: Carat scales: The most accurate method for measuring diamond weight is using a carat scale, which measures to the thousandth of a carat. This method is ideal for loose diamonds and provides precise weight measurements. Diamond caliper or gauge: These tools measure the dimensions of a diamond accurately, which are essential for applying estimation formulas. Presidium diamond gauge: This tool is specifically designed to measure the diameter and depth of diamonds for weight estimation. Measurement and estimation: For diamonds set in jewelry where direct weighing isn’t possible, estimation methods are used. This involves measuring the diamond’s dimensions (diameter, length, width, and depth) and applying specific formulas to estimate the carat weight. Different formulas are used depending on the shape of the diamond. For example: Round brilliant cut: Carats = Diameter2 × Depth × 0.00609664 Challenges in Measuring Diamond Weight Mounted diamonds: When diamonds are set in jewelry, it can be difficult to measure their exact weight due to obstructions from the setting. Estimations based on measurements may not be as accurate as direct weighing. Shape and cut variations: The shape and cut of a diamond can affect how its weight is perceived and measured. For instance, deeper cuts might weigh more but appear smaller than shallower cuts of the same weight. Accuracy limitations: Estimation methods provide approximate weights rather than exact figures. Factors such as girdle thickness and pavilion bulge can impact these estimates. Antique diamonds: Older cuts may have different proportions compared to modern standards, making it challenging to apply standard formulas accurately. Frequently Asked Questions How big is a 1-carat diamond? A single carat weighs 0.2 grams and has a diameter of approximately 6.5 mm when viewed from above. Note that the size of a diamond’s diameter (in mm) is not proportionate to the number of carats it weighs. How much is a 1-carat diamond worth? Many factors determine the value of a 1.00 ct diamond, including the cut, color, clarity, and shape of the stone, but prices start at around $1,800 and can increase to about $12,000. How much is a half-carat diamond worth? Prices for half-carat diamonds start at approximately $700 and increase massively depending on the diamond’s color, clarity, and cut. The most you can expect to pay for a diamond this size is about $2,000. How much does a five-carat diamond weigh? A 5-carat diamond weighs approximately 1.0 grams. How much does an eight-carat diamond cost? 8.00 ct diamonds are scarce and prized. You can expect to pay between $12,500 and $40,000 per carat for diamonds of this size if you ever come across them. How many carats is a flawless diamond? Flawless diamonds can weigh anything, but they are extremely rare and valuable. Of course, the price of flawless diamonds also increases with carat weight. The Regent Diamond, which is owned by the French state and is on display at the Louvre, has a carat weight of 140.64 (28.128 g) and had an estimated worth of 61,440,000 USD in 2016. It is the seventh-largest flawless diamond in the world, though it is said to be the most beautiful of them all. What is the difference between carat and karat? “Carat” (ct) is not the same as “karat” (K or kt). Although they both refer to units of measurement in jewelry, carat is a measure of gemstone weight, while karat is a measure of gold purity. How much does a diamond engagement ring cost? The cost of engagement rings varies enormously, even if you limit your choice to the popular round-cut diamonds, so arriving at a fixed amount is impossible. Some jewelers suggest that you spend at least two months’ salary on an engagement ring, while others argue it should be ten percent of your annual salary. However, there are no hard and fast rules on the subject, and the best option would be to buy an engagement ring that you can comfortably afford. Sometimes, this means forgoing a diamond ring altogether and opting for a more affordable stone like moissanite or white sapphire. Many couples also opt for colored gemstones instead of a traditional diamond ring. How do you insure an engagement ring? Most insurance companies will insure engagement rings as they would any other jewelry. However, because their sentimental value almost always outweighs their monetary value, accurately putting a price on these rings can be a bone of conjecture. Some insurers say that the current market value plus twenty-five percent is accurate, while others might suggest more or less. How many carats is the Hope Diamond? When the Hope Diamond was removed from its setting in 1974, it was found to weigh 45.52 carats, significantly more than the 44.5 carats it was previously valued at. It is known as a type l lb diamond, which is semi-conductive and phosphorescent. What are the most expensive diamonds in the world? Here are the ten most expensive diamonds in the world, according to size, sparkle, clarity, and ct weight: 1. The Maoussaieff Red Diamond. Discovered in Brazil in the 1990s and formerly known as the Red Shield, the Maoussaieff Red Diamond is the largest red-colored diamond in existence. Weighing 5.11 carats, it was displayed at the Smithsonian Institution in 2003 and 2005 as one of the most incredible diamonds in the world. With its brilliant triangular cut, this diamond is estimated at $8 million. 2. The Heart of Eternity. This Fancy Vivid Blue diamond was mined in South Africa. It was cut into a heart shape by the Steinmetz Group, and is priced at $16 million or thereabouts. 3. The Graff Pink. A rare pink 24.78 ct diamond that sold for $46 million at an auction in Geneva, Switzerland, in 2010. 4. The Wittelsbach Diamond. This Fancy Deep-Blue diamond with internally flawless clarity has been associated with Spanish and German royalty since it arrived in Europe in the 1600s. It was bought for $24.3 million in 2008. 5. The Winston Blue. Named after the celebrity jeweler Harry Winston, this Fancy Vivid Blue diamond was mined in South Africa. Pear-shaped and internally flawless, this jewel was bought for an estimated $23.8 million in 2014, setting a new world record for the most expensive blue diamond ever sold. 6. The Pink Star. Mined in South Africa in 1999 and originally named the Steinmetz Pink, the Pink Star is the world’s largest Fancy Vivid Pink diamond. Bought in Sotheby’s Auction in 2017 over a telephone bid for $71.2 million, this internally flawless 59.60 ct oval-shaped gem was then renamed the CTF Pink Star (in honor of the buyer’s late father). 7. The Centenary Diamond. Weighing 119.8 grams (or 599 ct) in its rough form, this massive gem was later cut into a modified heart shape, which reduced its carat weight to 273.85 ct. Nevertheless, the entire process took a team of experts 154 days to accomplish. The diamond was insured for over $100 million at the time of its unveiling in 1991, but it has never been publicly appraised. 8. The Hope Diamond. Priced at $200-$350 million, this 45.52 ct Fancy Dark Grayish-Blue antique cushion cut diamond is believed to have been discovered in India in the 1600s. It was bought by King Louis XIV in 1668 and then stolen, along with the crown jewels, during the looting that took place in 1792 after King Louis’s demise. Later, it resurfaced in London and was purchased by Harry Winston in 1949, who donated it to the Smithsonian Institution. Unfortunately, because its previous owners all met with ill fate, the Hope Diamond is rumored to be cursed. 9. The Cullinan Diamond. Also known as the Star of Africa, the Cullinan Diamond is the largest rough diamond of gem quality ever found. It was discovered in Cullinan, South Africa, in 1905 and was gifted to King Edward VII. Valued at around $2 billion, it weighed approximately 621.35 grams (3,106.75 ct) before it was cut into nine “smaller” stones, the largest of which is the Cullinan I at 530.2 ct. 10. The Koh-I-Noor. This colorless oval-shaped gem weighing 105.6 ct is steeped in mystery and legend. It was found in India in the 1300s and is also called the Mountain of Light and the Diamond of Babur. Currently, the stone forms part of the British crown jewels and is set in the crown of the Queen Mother. What is a good carat weight? The ideal carat weight is one that showcases the diamond’s beauty. Does carat weight impact diamond size? Carat weight is not necessarily reflective of a diamond’s size. For example, two diamonds of equal carat weight may appear bigger or smaller than one another, depending on their other attributes. In particular, the cut grade and top diameter of each gem play a prominent role in determining their size. These attributes are known as the diamond’s dimensions. You can use a diamond size chart to get an idea of the ratio of the different carat weights to a diamond’s physical size in millimeters (mm). How much do diamonds weigh? There is no standard weight for diamonds. One carat is equal to roughly 200 milligrams (0.20 grams) and is subdivided into 100 points for accuracy. Therefore, a 0.10 carat diamond weighing one-tenth of a carat may be referred to as “10-points”. What is the meaning of a full carat? A full-carat diamond is equivalent to 200 milligrams or 100 “points”. In other words, it weighs one whole carat (1.00 ct). Diamonds that weigh below one carat are measured by their points value alone. How do you tell if a diamond is real? The only way you can distinguish between a real diamond and a fake is to view it under a magnifying glass. If you can see imperfections (called inclusions) in the stone, the diamond is real. However, it also takes a trained eye to know what characteristics to look for. Alternatively, if you are buying a diamond from a shop, you can ask to see its diamond certificate. Also known as a diamond grading report, it confirms the identity and quality of the gem, assuring you that you are getting what you pay for. What is the most desirable carat weight for an engagement ring center stone? Popular weights for diamond engagement rings range from 1.00 ct to 2.00 ct, although peaks are observed between 0.7 ct and 0.79 ct (averaging around 0.75 ct). The average in the United States is 1.00 ct; in the UK, 0.60 ct; in the rest of Europe, it’s around 0.50 ct. As you can see, there is a considerable amount of variation in diamond carat size for engagement rings. Thus, there are no set rules regarding the “ideal” proportions of a center stone for an engagement ring – it is more a question of personal preference and price. Also, bear in mind that engagement ring settings affect the appearance of the stone and that you need to consider what the finished piece will look like on your partner’s finger. If you are unsure about the design, ask your jeweler for advice on the different weights and settings. Alternatively, you could consult a diamond carat guide or carat weight chart/table. What are the different cuts and shapes of diamonds? Popular diamond cuts and shapes are the round brilliant cut (the round diamond or round cut is the most popular cut for engagement rings), the princess (or square) cut, the emerald cut, the cushion cut, the radiant cut, the Asscher cut, the pear cut, the oval cut, the heart shape, and the marquise cut. Other cuts that are not often seen and patented to specific brands include the Asprey, eighty-eight, Ashoka, jubilee, Lily, Princess Plus, Royal Asscher, bead, and Criss cuts. All these shapes (including the ones above) come in different ct sizes for diamonds and other stones. Note: While we strive to provide accurate pricing information, please be advised that multiple factors influence diamond prices. The prices listed are for reference only and are subject to change without notice.
