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Even though there are many factors that determine the quality of a diamond, many buyers focus on its carat weight.
Diamonds are available in a variety of carats, and it doesn’t have to be a round number. But some buyers are interested in a one or two carat diamond and want to understand how the difference in weight affects its appearance and performance.
The main differences between a one and two carat diamond are a two carat diamond has a larger surface area, and you’ll have to choose higher color and clarity grades for it to appear eye-clean. The price also substantially increases as you move from one to two carats.
We’ll provide a full comparison of one versus two carat diamonds, including their sizes, cost, grades across the four Cs, and settings, so you’ll know which is right for you.
When someone refers to the size of a diamond, they typically aren’t referring to its dimensions, such as length and width.
Instead, its size is a unit of weight called a carat, which equals 0.2 grams.
So a one carat diamond weighs 0.2 grams and a two carat diamond weighs 0.4 grams.
Carat weight is divided into 100 points.
If you’re searching for a diamond with a carat weight below two, they’re available at nearly every point between whole numbers, so your choice isn’t necessarily between one and two carats.
For example, you could choose a 1.30 or 1.45 carat diamond.
But it’s also worth noting the different dimensions between diamonds of various carat weights.
One carat diamonds generally have a 6.5mm diameter, but the exact measurement varies between diamonds.
For example, check out this round cut.
Its length is 6.25mm, and its width is 6.21mm.
As a comparison, this one-carat round cut is 6.22mm x 6.32mm.
To the naked eye, these differences aren’t obvious.
You might assume the dimensions of a two carat diamond are double that of a one carat, but that’s not the case.
Two carat diamonds often have diameters of 8.10mm.
The example below is 8.14mm x 8.07mm.
Similar to a one-carat diamond, exact dimensions for two-carat diamonds depend on the cut.
But the most common question is whether there’s a noticeable difference in size between one versus two carat diamonds when they’re viewed in a normal setting.
The answer is a two carat diamond is noticeably larger than a one carat diamond. If you’re most concerned about its appearance, the distinction won’t go unnoticed.
There are many traits that determine a diamond’s price, but carat weight is often the most impactful. You can expect an increase in cost with every point, but there are certain thresholds where there’s an even higher premium.
Additionally, the price of a diamond doesn’t increase linearly with carat weight. Instead, it’s exponential.
To create the chart below that shows how carat weight impacts diamond price, we analyzed prices for more than 500 diamonds with the same grades but different carat weights.
It demonstrates how two carat diamonds are more than twice as expensive as one-carat diamonds.
To provide another example of this comparison, we examined prices for 291 one- and two-carat diamonds from James Allen, an online jewelry retailer.
They all had the following qualities:
- Cut: Very good
- Shape: Round
- Color: G
- Clarity: VS2
The one-carat diamonds cost an average of $5,642, with a range of $4,600-$6,050.
The two-carat diamonds were priced at an average of $26,489. The range was $23,030-$32,750.
This demonstrates how two carat diamonds typically cost 3.5 to four times as much as one carat diamonds.
Jewelry vendor Ritani conducted research on the most popular carat weights for engagement rings.
The study found the average is 1.08 carats, with the range of 1.0 and 1.09 being the most common at 19 percent. This demonstrates how one carat diamonds are more popular than two carats.
In fact, only four percent of diamonds in the survey weighed between 2.0 and 2.4 carats.
The Knot performed their own research and found the average is 1.5 carats, and only 25 percent are two carats or above.
The reason one carat diamonds are more popular for engagement rings compared to two carats is because of cost. Carat weight has one of the strongest correlations with cost, and as you’ve learned, it increases exponentially.
Diamonds close to one carat are often at the price most buyers are willing to spend.
The research also found 10 percent of buyers choose a diamond slightly under one carat, between 0.90 and 0.99. This is because there’s a premium when a diamond hits one carat.
Many buyers want the satisfaction of a single carat, which means the relative price between a 0.95-carat and one-carat diamond is often higher than what you’d find when a difference of 0.05 carats doesn’t hit a whole number.
This reduces the popularity of engagement ring diamonds, relative to expectations, where the carat weight is one or two.
The color of a diamond refers to the presence of any yellow or brown tints. Colorless diamonds are considered the most valuable, especially for engagement rings.
This quality is graded on a scale developed by the Gemological Institute of America (GIA), that includes five categories:
- Colorless (D-F)
- Near colorless (G-J)
- Faint (K-M)
- Very light (N-R)
- Light (S-Z)
The exact color grades you should consider depend on whether you’re choosing a one or two carat diamond. That’s because in your aim to find one that appears colorless to the naked eye, the size of its facets affect how color shows.
For example, we recommend starting your search with J color diamonds if it weighs one carat. It’s the lowest position in the near colorless section.
The reason it’s the right place to begin is because of the strong value it offers. In cases where its color is indistinguishable with a D, E, or F diamond, you’ll save on cost by moving down the color scale.
Check out the comparison of two diamonds below.
Even in those high-resolution images, they’re difficult to tell apart.
In fact, you can expect to save up to 50 percent by choosing a J or I diamond compared to one with a D color grade.
For a two carat diamond, start with the G-I range. It’ll likely have noticeable shades of yellow if you choose J or below.
As an example, here’s a two-carat diamond with a J color grade.
The hint of yellow is visible, especially compared to this G color diamond.
As with one carat diamonds, you’ll save on price by selecting a lower color grade, but it’ll appear identical to one with a colorless grade.
One caveat is for fancy shapes with step-cut facets like Asscher or emerald cuts. Their elongated facets tend to show more color, so you may have to choose one color grade higher compared to a round cut.
When comparing the clarity grades of one versus two carat diamonds, many of the same principles as deciding on color are applicable.
Clarity grades indicate the presence of inclusions, or blemishes, in a diamond’s facets. There are many types of inclusions, such as:
- Twinning wisps
- Etch channels
They’re present in diamonds of every size, from one or two carats and every weight in between.
The GIA clarity scale starts at flawless and ends at I3, where each grade below flawless conveys more impactful inclusions.
To find the best value for one and two carat diamonds, we recommend avoiding the highest grades. Your goal isn’t to find one without flaws visible at 10x magnification.
Instead, it’s best to find one that’s eye-clean and where the inclusions don’t affect its durability or brilliance.
For two-carat diamonds, start your search at VS1. View them in person or through high-quality images to learn if the inclusions are apparent.
For one-carat diamonds, you might find one that earned an SI1 clarity grade but is still eye-clean. If you want more certainty, move up to VS2.
This diamond provides a helpful example.
If you didn’t know its clarity was VS2, you’d think it was flawless. Even when you rotate the image, the inclusions are hard to find.
A diamond’s cut is the factor that most affects its brilliance. Its cut grade is a combination of several traits, such as proportions, symmetry, girdle thickness, and dimensions.
Cut grades for round-cut diamonds range from excellent to poor.
We recommend excellent cuts for one- and two-carat diamonds. You want to maximize its light performance, and even colorless and flawless grades won’t compensate for a poorly cut diamond.
You’ll pay a premium for the excellent cut, but if you want to avoid that charge, the lowest you should ever go with is a “very good” grade.
Unlike color or clarity, it’s difficult to judge a diamond’s cut based on an image. Instead, you should read its report for the details.
We’ll walk you through the process for this one-carat diamond.
In the second section of the left panel, you’ll find its grades across the four Cs. At the bottom, notice how its cut is excellent.
In the section below, you’ll find its polish and symmetry grades, which are excellent and very good, respectively.
The middle panel shows its proportions.
Based on this GIA report, you can have confidence in the quality of its cut.
As a counter example, check out the cut grade of this two-carat diamond.
Even though its polish is excellent, its symmetry, proportions, and very thick girdle bring its cut down to “good.”
Despite its strong color and clarity grades, its cut would result in a lack of brilliance.
Once you’ve decided on a one- or two-carat diamond, it’s time to select the perfect setting.
There are many styles available, and almost all will fit both carat weights. But there are factors to consider because of their different dimensions.
If you’re paying the premium for a two-carat gem, you want to show it off. That’s why you might choose a high setting, where the diamond sits far above the ring to collect and return the most light.
Solitaire settings are also a popular choice for large diamonds. They allow you to best display the gem, without smaller diamonds on the ring detracting from it.
For example, check out this two-carat diamond in a knife edge setting.
The thin band makes the diamond appear even larger. It’s a striking combination that focuses all the attention on the two-carat diamond.
For one-carat diamonds, it’s common to opt against solitaires and instead choose a setting with additional diamonds in the form of pave or a halo.
In the setting below, a halo surrounds a one-carat diamond.
It creates the illusion of a heavier diamond because from a distance, they blend together.
There’s also pave on the shank, which means the piece will sparkle from every angle.
Whether you land on a diamond that weighs one or two carats, pair them with several types of settings to learn which style fits your taste.
Should You Choose a 1 or 2 Carat Diamond?
Comparing one carat versus two carat diamonds involves understanding how their differing weights impacts the rest of its qualities.
While the distinction between their visual sizes is obvious, how its larger surface area affects traits like color and clarity is more complex.
Here are some tips to help you choose.
Consider a one-carat diamond if:
- You want to save a significant amount on cost compared to two carats
- You’re choosing a setting that features other diamonds and aren’t concerned that it may detract from its prominence
- You plan to put that savings toward higher clarity, cut, or color grades or a more elegant setting
A two-carat diamond might be right for you if:
- You’re willing to pay a premium for a larger diamond
- When choosing its color and clarity, you select high enough grades that it appears flawless and colorless to the naked eye
- You’re interested in placing it in a solitaire setting, where it commands the most attention
Explore one- and two-carat diamonds at in-person and online jewelry retailers. Understand you’ll likely find more one-carat diamonds to choose from because of their popularity.
But either way, by pairing them with various settings, you’ll create the right diamond ring for you.
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