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Diamond Carat Guide

Explore the fundamentals of diamond carat, explaining how this universal measure of weight directly influences a diamond's visual size, rarity, and market value.

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In This Guide
  • What Is a Carat?
  • What Is Carat Weight?
  • How Does Carat Weight Affect a Diamond?
  • What Does CTTW Mean?
  • Difference Between Diamond Carat and Size
  • How Much Does a 1, 2, or 3 Carat Diamond Cost?
  • Tips to Make Your Diamond Look Bigger
  • Diamond Carat FAQs
Lab diamond size chart with measurements and a pencil for scale on a white background

What Is a Carat?

In the diamond industry, a “carat” is a universal measure of gem weight. One carat equals a specific weight of 200 milligrams, or 0.2 grams. The word “carat” derives from the carob seed, which ancient gem merchants used as natural counterweights on their scales.

Today, the term “carat” is used to measure the weight of diamonds and gemstones and is simply one of the four Cs (cut, clarity, color, and carat) of diamond quality. However, keep in mind, carat is weight and does not necessarily refer to size. A large carat weight does not mean a diamond will look larger, as that depends on cut and shape as well.

Five lab diamonds of different shapes and sizes on a dark background

What Is Carat Weight?

Carat weight is only specific to the weight of the diamond, not the dimension of the diamond. As previously mentioned, 1 carat is 0.2 grams. Diamond carat weight is typically measured to the hundredth decimal, and is one of the most visible pricing factors when choosing a diamond.

But here’s where it gets interesting: two diamonds with the same carat weight may actually look very differently in terms of size depending on how they've been cut. A diamond with a deep cut allows more of its weight to be carried below the depth that is going to affect visual size, and will appear smaller from the top compared to a diamond with a shallower cut with the same carat weight.

That’s why carat weight is only part of the full picture when selecting a diamond — especially when it comes to visual size and brilliance.

Close-up of round lab diamonds on a light background

How Does Carat Weight Affect a Diamond?

Carat weight is a major consideration for the look and price of a diamond. As the carat weight goes up, the rarity, and thus the price, goes up. While larger diamonds are not just heavier, they are also more rare to find in natural form, (or grow from a lab more perfect) which is why a 2 carat diamond is many times more valuable than a 1 carat diamond of equal value.

But carat weight is only part of the story. Carat weight is just one of the 4Cs (Carat, Cut, Color, Clarity). A heavier diamond with a bad cut wouldn't look as visually large, or have as much sparkle, as a lighter diamond with proper proportions.

In short:

• Higher carat weight = more perceived prestige and presence, but

• Cut quality, diamond shape, and setting design all work together to determine how "big" and brilliant the diamond actually appears.

Gold engagement ring with a large lab diamond and smaller lab diamonds on a light gray background

What Does CTTW Mean?

CTTW is short for "Carat Total Weight" (sometimes written as "CTW"), and it refers to the combined carat weight of all diamonds in a piece of jewelry. the total carat weight of all diamonds in a piece of jewelry. CTTW is common in jewelry that has several stones set together, such as halo rings, pavé bands, tennis bracelets, or diamond earrings.

For example:

• A halo engagement ring with a 1 carat center diamond and 0.25 carats of surrounding stones will have a CTTW of 1.25 carats.

• A pair of diamond studs identified as 1.00 CTTW means each earring probably has about a 0.50 carat diamond.

CTTW is important when comparing multi-stone pieces, but it doesn’t reflect the size of the center stone alone. So, always verify the carat weight of the individual stones if you're interested in the size of an individual stone in jewelry like a solitaire ring.

Hand wearing multiple lab diamond engagement rings on a neutral background

What’s the Difference Between Diamond Carat and Diamond Size?

It’s a common misconception that carat and size are the same—but they’re not.

• Carat refers to weight. One carat equals 0.2 grams.

• Size refers to the diamonds physically proportions--diameter, depth and how much physical surface area the diamond covers when viewed from above (also known as its “face-up size”).

Why does this matter? Because two diamonds with the same carat weight can appear different in size depending on:

• Cut quality: A deep cut diamond may look smaller than a shallow cut diamond even though they are both a one carat.

• Shape: Elongated shapes like oval, marquise, and pear often look larger than round or princess cuts with the same weight.

Understanding the difference will help you find a diamond that looks the way you want it to look despite the carat number being the same.

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Which Diamond Shapes Look Biggest for Their Carat Weight?

Not all diamond shapes are created equal when it comes to visual size. Some shapes offer more face-up area, giving the illusion of a larger diamond without increasing the carat weight.

Here are the top shapes that look biggest for their carat weight:

• Marquise: The elongated body and pointed ends give marquise diamonds the largest finger coverage per carat.

• Oval: Slightly rounded and elegant, oval diamonds appear larger than rounds due to their stretched surface area.

• Pear: The teardrop shape of pear diamonds mixes brilliant cut with linear appealing elongation.

• Emerald: The rectangular step-cut facets of emerald diamonds maximize spread and elegance, especially at higher carat weights.

• Radiant: With trimmed corners and brilliant-cut facets, radiant diamonds combine sparkle with a large face-up look.

When size impact matter, there is a great deal that shape selection can provide from a value perspective—so if you want to maximize visual bang for your buck, elongated or fancy cuts are worth considering.

What’s the Best Carat Size for My Budget?

The ideal carat size depends on what matters most to you: size, quality, or overall appearance. Below are some ways to use your budget wisely without compromising on beauty and allowing you to choose the right diamond carat size:

1. Consider “Magic Sizes”

In general, diamond prices increase significantly beginning at certain weights like 0.5 carats, 1 carat, 1.5 carats and 2 carats. Opting for just under these thresholds (e.g., 0.90ct or 1.40ct) can offer a near-identical look for noticeably less.

2. Choose Lab Grown Diamonds for More Carat for Less

Lab grown diamonds can cost up to 50% less than mined diamonds of the same quality, meaning you can size up without breaking your budget.

3. Prioritize Cut Over Carat

A well-cut 1.0 carat diamond can appear larger and sparkle more than a poorly cut 1.2 carat diamond. Always select excellent or ideal cut grades whenever possible.

4. Balance the 4Cs

If size is your main priority, consider slightly lower clarity or color grades in exchange for more carat weight. Lab diamonds with SI1 clarity or G-H color still look beautiful, and offer better size for your spend.

5. Set for Impact

Using halo, pavé, or thin-band solitaires can make your diamond look larger without having to increase carat weight.

Whether your budget is $1,000 or $10,000, it’s all about finding the right balance between sparkle, size, and style.

How Does Cut Quality Impact a Diamond’s Carat?

Cut quality is one of the most influential factors on how big and how brilliant your diamond will appear. Two diamonds with identical weights can appear very different in size and brilliance due to their cut quality, the one with a better cut will almost always look bigger and more brilliant.

1. Cut Affects Light Performance

Well-cut diamonds are great at reflecting light causing them to sparkle more than poorly cut diamonds that leak light causing them to be dull and sometimes appear smaller than their weight.

2. Cut Affects Face-Up Size

Deep-cut diamonds hide a lot of weight into the bottom (pavilion) so they appear smaller when viewed from the top (face-up). On the other hand, shallow but well-proportioned cuts have the potential to make the diamond appear larger by giving the diamond a wider appearance.

3. Round vs Fancy Shapes

Round brilliant diamonds tend to be cut for maximum fire and brilliance. Fancy shapes like oval, pear, and marquise can appear larger for their weight but vary more in cut quality—so choose carefully.

4. Always Look for “Excellent” or “Ideal” Cut Grades

At Lucenjuri, we prioritize Excellent and Ideal cut diamonds, because cut quality doesn’t just affect sparkle—it determines the overall visual appearance on the stone.

How Much Does a 1, 2, or 3 Carat Diamond Cost?

As a diamond increases in carat weight, the price increases exponentially, especially over key size thresholds such as 1, 2, or 3 carats. However, lab grown diamonds can provide you with many more carats for much less. But how much should you really expect to spend on lab grown diamonds?

Pricing Overview (Lab Grown vs. Mined)

At Lucenjuri, our lab grown diamonds typically cost 80–95% less than their mined counterparts of the same size and quality. So you can buy a larger stone and/or a higher clarity/color and still be well within budget. 

Carat Weight Approx. Price Range Price Factor Considerations
1 Carat $300–$1,200 Depends on cut, color, clarity, and shape
2 Carat $800–$3,000 Higher pricing if color/clarity is top-tier
3 Carat $1,200–$6,000 Premium shapes and ideal cuts can increase cost

Why Larger Diamonds Cost More per Carat

Larger diamonds are rarer, even among lab grown stones. The higher the carat, the more difficult it is to grow without imperfections, so the price-per-carat also increases.

By choosing lab grown diamonds and smartly balancing the 4Cs, you can unlock incredible beauty and size at a price that works for you.

Tips to Make Your Diamond Look Bigger

Want your diamond to turn heads without upsizing the carat? These clever design and styling tips can make your diamond look noticeably larger—no extra weight needed.

Choose an Elongated Shape

Diamonds in the oval, marquise, emerald and pear shapes usually have more surface area than a round diamond of the same carat weight. The elongated shape gives you more coverage for your finger and it can provide a bolder statement.

Go for a Halo Setting

By placing a halo (or circle) of smaller diamonds surrounding your center stone will create the illusion of a larger center stone. So, the halo setting is one of the best ways to increase sparkle and size all at once.

Opt for a Thin or Tapered Band

A delicate, slim band (also called a “petite” band) will draw your eye to the center diamond, and it will also create contrast and help the center diamond appear larger.

Use a Bezel Setting with Minimal Metal

A bezel can make the diamond appear more defined and prominent. Just choose a light bezel or floating bezel that doesn't cover too much of the stone.

Prioritize Excellent Cut Quality

Regardless of the carat weight, the better the cut of the diamond the more light it will reflect, and the more brilliance it will have, ultimately the larger and more dynamic it will look.

Consider White Metals for Contrast

White metals such as platinum or white gold can provide a bright seamless effect, which can help with sparkle and size of the diamond.

By combining strategic shape, setting, and metal choices, you can achieve a look that appears significantly larger—without having to increase your carat size or your budget.

Diamond Carat FAQs

How is diamond carat measured?

Diamond carat is measured as a unit of weight, not size. One carat equals 0.2 grams (200 milligrams) and is divided into 100 points—so a 0.75 carat diamond equals 75 points. Professionals or gemologist use micro-balance scales with precision to guarantee this accuracy.

Can two diamonds with the same carat weight appear different in size?

Yes! A diamond's shape, cut, and depth can contribute to how big it seems. A shallow, well-spread diamond can look bigger than one that is set deeper, but are the same carat weight.

Is a higher carat weight always better when choosing a diamond?

Not necessarily. More carat weight gives you a large look but don't forget that cut, clarity, and color can all influence beauty and value. A smaller diamond with an excellent cut can outshine a larger one with lower quality.

Are there certain diamond shapes that appear larger for the same carat weight?

Yes. Oval, Pear, Marquise, or Emerald cuts have larger surface areas, making them look larger than the equivalent round or cushion shape of the same carat.

What does “CTTW” mean in diamond jewelry?

CTTW means “carat total weight” and refers to the combined weight of all diamonds in a piece of jewelry. For example, a halo ring with a 1 carat center stone and 0.50 carats of side stones would be marked as 1.50 CTTW.

How many carats should I choose for an engagement ring?

It depends on your budget, style, and preferences. 1-2 carats is the most popular range and provides good finger presence without being overwhelming when worn every day.

Does finger size affect how big a diamond looks?

Yes. Choosing the right ring involves considering how it complements your hand's unique features. A diamond will appear larger on a smaller finger. On larger fingers, you may want to be more inclined towards a larger carat size or elongated shapes like oval or marquise to balance proportions. So it’s important to select an engagement ring that suits your hand shape and personal taste.

How much do diamonds cost by carat?

Diamond prices tend to increase exponentially based on their carat weight. A 2 carat diamond may be much more expensive than two 1 carat diamonds because it is rarer. Lab-grown diamonds provide substantially more carats for less money than mined diamonds.

How do I make a smaller carat diamond look bigger?

Choose halo settings, thin bands, or elongated shapes, and prioritize excellent cut quality. These design elements can dramatically enhance your diamond’s visual size without increasing carat weight.

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