Carat is one of the most important of the four C's in diamond buying. It is the globally recognized standard for the weight of a diamond (not to be confused with karat, which measures gold purity). Many brides-to-be may argue that carat is the most important aspect, as it significantly impacts the appearance of an engagement ring. You'll frequently hear about carat weight while shopping for an engagement ring, so here are the key points to know, including how much a carat weighs and how it's priced. For a quick understanding of diamond carat, watch our co-founder Anubh discuss this topic below.
TABLE OF CONTENTS |
| How much does a diamond carat weight? |
| Diamond carat size comparison |
| Diamond MM chart |
|
Carat price effect: What does a diamond carat weight? |
| Diamond Carat and Price |
| What is the average diamond carat weight? |
| How important should carat be when buying a diamond? |
| Diamond carat sizes on hand |
How much does a diamond carat weight?
A 1 carat (ct) diamond weighs 0.20 grams. Contrary to popular belief, carat refers to the weight of the diamond, not its size. A diamond's size is measured in millimeters, length by width — the diameter of the diamond. It typically takes about 250 tons of rock mining to produce a single 1 carat diamond, contributing to their rarity and expense.
Diamonds come in various shapes and carat weights. A diamond cutter’s highest priority is to maximize carat weight. The larger the diamond, the rarer and more expensive it is. Diamonds are weighed very precisely, to the nearest 0.01ct.
Before the universal adoption of the carat in 1907, various measurements were used for diamonds. At one point, carob seeds were used because it was believed, albeit incorrectly, that the mass of each seed did not vary much. Over time, carat weight became standardized. It is now a common point of reference on the certificate of any diamond, regardless of the certifying institution.
Diamond carat size comparison
Each diamond is unique, but it is possible to approximate visual size because modern diamonds are cut with precision using machines. Within each carat range, diamonds have an average size in millimeters.
Well-cut round diamonds have less depth compared to well-cut fancy-shaped diamonds (any shape other than round). For instance, a 1ct round diamond typically measures around 6.40mm in length and width, while a 1ct princess diamond measures about 5.50mm.
Fancy shapes often carry more weight and appear smaller than round-cut diamonds of the same carat weight. As a result, round-cut diamonds tend to be more expensive than fancy shapes of the same carat weight.
Visually, it is challenging to distinguish between diamonds that vary by 5 to 10 percent in carat weight. For example, a 0.95ct diamond and a 1ct diamond will look nearly identical. This is something to consider if you want the appearance of a 1ct diamond without paying the higher price for that popular weight.
A diamond that is cut too deep may appear smaller than a diamond of lower carat weight. When considering carat weight and millimeter size, it's also important to look at the length-to-width ratios for each diamond shape. These ratios will help you understand if a diamond is too shallow or too deep, or if it has desirable proportions. A deeply cut 1ct diamond might look smaller than a shallow-cut 0.95ct diamond.
Remember, carat refers to weight, so a diamond's measurement in millimeters can vary depending on how it's cut. Choose diamonds that are well-cut, as they tend to have less depth and more spread. This means their measurements are larger, making the diamond appear visually larger than its carat weight.
Diamond MM Chart
Carat price effect: What does a diamond carat cost?
Diamond pricing increases exponentially, not linearly, as carat weight increases. Once a diamond hits its critical weight, the price jumps. The critical weights are 0.30ct, 0.40ct, 0.50ct, 0.70ct, 0.90ct, 1.00ct, 1.50ct, 2.00ct, 3.00ct, 4.00ct, 5.00ct, and 10.00ct.
Diamond cutters strive to keep the diamond weight at or above each critical weight. Diamond manufacturers and suppliers are aware of this strategy, so they price their diamonds accordingly. It might be wise to buy a 0.95ct diamond instead of a 1 carat diamond, but the former option is difficult to find. At With Clarity, our team of expert gemologists can help you track down the perfect stone in the right carat size.
CARAT PRICE FOR LAB GROWN DIAMONDS
When shopping within the same budget, consider lab diamond comparisons. Lab-grown diamonds possess the same physical, chemical, and optical properties as natural diamonds. The primary difference is their origin: natural diamonds are formed in the earth, while lab diamonds are created in controlled laboratory environments. Refer to our table below to see price comparisons between round natural and lab diamonds. Explore our certified lab diamond catalog. Values are estimated and can vary based on our inventory.
YOU NEED TO UNDERSTAND "MAGIC SIZES"
You can save a significant amount on your engagement ring by avoiding "magic sizes"—those weights that are more expensive due to high demand and critical weight categories. Although there is no visual difference between a 1.99ct diamond and a 2.00ct diamond, the latter can cost substantially more because it falls into a "magic size" category. Diamonds that don't fall into these categories are called "off-size diamonds," and they may be the key to getting the engagement ring of your dreams at a better price.
What is the average diamond carat weight?
The average diamond carat weight is 0.90ct.
Aim to purchase a diamond just below the critical weight where prices increase significantly. For instance, choosing a 0.95ct diamond instead of a 1ct can save you money, as 1ct is a critical weight with an exponential price increase.
How important should carat be when buying a diamond?
Carat weight is often the most visual and popular of the 4 C's, making it a common first consideration for many. While we recommend prioritizing diamond cut, ultimately, it depends on your preferences. Remember, carat weight alone isn't everything; it must be balanced with the other factors.
When pricing diamonds, consider carat weight on one side and the remaining 3 C’s — cut, color, and clarity — on the other. To stay within your budget, increasing the carat may require compromising on the other C’s. Conversely, if you focus on enhancing cut, color, and clarity, you may need to choose a lower carat. A larger carat size will make a more substantial visual impact, but if you don't prioritize cut and clarity, the diamond will have less sparkle.
Check out our diamond price estimator to understand the approximate pricing for different diamond sizes and attributes.
Diamond carat sizes on hand
Below, you can see how different diamond carat sizes look on a hand. When shopping, consider both her hand and finger size. Keep in mind that most fancy diamond shapes like emerald, oval, and pear will appear larger on the hand than a round diamond of the same carat weight. Learn more about the various diamond shapes to understand which is the best fit for her ring. Additionally, once set within a ring, the diamond carat weight can look even larger, depending on the ring style.
Below are round diamonds that measure 0.25ct, 0.50ct, 0.75ct, 1.00ct, 2.00ct, 3.00ct, 4.00ct, and 5.00ct respectively.