TL;DR: CTW means carat total weight — the two diamonds in a pair added together. For everyday wear in Sandy Springs, most clients choose 0.50 ctw–1.00 ctw pairs. Want a bigger look? Go 2.00 ctw+. We also set 3.00 and 4.00 ctw studs — lab-grown puts statement sizes within reach. Lab-grown or natural options in 14k, 18k, or platinum, and you can see our diamond stud earrings here.

Key Facts

• Classic daily sizes: 0.50 ctw and 1.00 ctw (pair)
• Statement sizes: 2.00–4.00 ctw (pair)
• Biggest looks: 3.00 and 4.00 ctw lab-grown studs — that is a 1.50 to 2.00 ct stone on each ear
• Backs by size: friction under 1.00 ctw, screw-back from 1.00 up to 2.00 ctw, guardian backs at 2.00 ctw and above
• Lab-grown vs natural: identical look; lab-grown lets you go larger for budget
• Set in Sandy Springs: our artisan jewelers mount every pair and check it over before it leaves the bench

Visual Reference: Actual Size on Ear

Diamond Stud Earring Size Chart: Carat to Millimeter

CTW refers to the combined carat weight of both stones in the pair. Millimeter sizes are approximate for round brilliant-cut diamonds.

Diamond stud earring size guide — pair carat total weight (CTW), per-ear carat weight, and approximate millimeter diameter for round diamonds

Pair Total (CTW)	Per Ear (ct)	Approx. Diameter (mm)	Typical Look	Shop
0.20 ctw	0.10	≈3.0 mm	Tiny / second hole	View
0.25 ctw	0.125	≈3.3 mm	Subtle daily	View
0.33 ctw	0.165	≈3.6 mm	Light daily	View
0.50 ctw	0.25	≈4.1 mm	Classic everyday	View
0.75 ctw	0.375	≈4.7 mm	Noticeable sparkle	View
1.00 ctw	0.50	≈5.2 mm	Bold everyday	View
2.00 ctw	1.00	≈6.5 mm	Statement	View
3.00 ctw	1.50	≈7.4 mm	High-impact	View
4.00 ctw	2.00	≈8.2 mm	Luxury statement	View

Note: the millimeter size can vary with how a diamond is cut and finished — jewelers call that its make — and with the setting style. Princess, radiant, and cushion shapes can look a little different in size when you view them from the front, which is called the face-up size. These measurements are for round brilliant diamonds cut to ideal proportions.

Millimeter to Carat: Reverse Lookup

Measured a stud you already own, or found a millimeter size on a tag? Start with the millimeter number below and read across to the carat weight. These are round diamonds.

• About 3.0 mm — roughly 0.10 ct on each ear, 0.20 ctw for the pair
• About 3.3 mm — roughly 0.125 ct on each ear, 0.25 ctw for the pair
• About 3.6 mm — roughly 0.165 ct on each ear, 0.33 ctw for the pair
• About 4.1 mm — roughly 0.25 ct on each ear, 0.50 ctw for the pair
• About 4.7 mm — roughly 0.375 ct on each ear, 0.75 ctw for the pair
• About 5.2 mm — roughly 0.50 ct on each ear, 1.00 ctw for the pair
• About 6.5 mm — roughly 1.00 ct on each ear, 2.00 ctw for the pair
• About 7.4 mm — roughly 1.50 ct on each ear, 3.00 ctw for the pair
• About 8.2 mm — roughly 2.00 ct on each ear, 4.00 ctw for the pair

If your measurement falls between two rows, the carat weight falls between them too. Bring the earrings in and we'll measure them for you.

3/4 Carat vs. 1 Carat Diamond Studs: Side by Side

The most common question we hear in Sandy Springs is whether to go 3/4 carat or a full carat. A 3/4 ctw pair (≈4.7 mm each) reads as elegant, noticeable sparkle that stays office-appropriate. A 1.00 ctw pair (≈5.2 mm each) is bolder — you see it across the room. It does cost more, though less of a jump than most people expect, and less again in lab-grown diamonds. If you want subtle, choose 3/4 ct. If you want presence, choose 1 ct. You can compare both sizes here.

How to Choose Diamond Stud Earring Size

Choosing stud size is about balance: your ear, your hairstyle, your lifestyle, and your budget. In Sandy Springs, most clients land on 0.50–1.00 ctw for daily wear. For a special occasion or a gift, 2.00–4.00 ctw is worth a look. Lab-grown diamonds cost less per carat, and that is what makes those larger sizes practical.

Lab-grown studs have the same brilliance, hardness, and sparkle as natural diamonds. They cost less, so the same budget buys a larger size. Natural diamonds are valued for their rarity and for tradition. Both come with a grading report from GIA or IGI.

You can browse our diamond stud earrings whenever you like.

Lab-Grown vs Natural Diamond Studs

Both lab-grown and natural diamonds are real diamonds — chemically, optically, and physically identical. The choice comes down to priorities:

• Lab-grown diamond studs: Same sparkle, graded by an independent lab such as GIA or IGI, and priced well below a natural diamond of the same size. That is what puts 2.00–4.00 ctw statement sizes within reach.
• Natural diamond studs: Valued for geological rarity and for tradition, and graded by those same independent labs. Ideal for milestone gifts or heirloom pieces.

Both options are available at Farsi Jewelers in 14k gold (white, yellow, rose), 18k gold, and platinum settings. Our diamond studs come with a grading report from GIA or IGI — ask us and we'll confirm the report on any pair you are considering. Every pair is set by our artisan bench jewelers, with a GIA Graduate Gemologist on site.

Earring Back Types: Which Is Right for You?

We pick the back by stud size, and the rule is simple:

• Friction (push-back) — under 1.00 ctw: Simple and low-profile. Best for smaller studs and everyday wear.
• Screw-back — 1.00 up to 2.00 ctw: A threaded post that twists shut, for added security. A good choice if you are active.
• Guardian back — 2.00 ctw and above: A locking back, also sold under the name La Pousette. This is the most secure option, and the one we recommend for larger studs and for travel. It also spreads the weight of a bigger stone more evenly.

We match the back type to your stud size, ear anatomy, and daily routine during your fitting appointment.

Visit Us in Sandy Springs

Come see these studs on your own ear in our Sandy Springs showroom. We'll show you what is in the case, and we can bring in any size on this chart so you can compare. Seeing diamonds on your ear is the best way to choose — photos and charts only tell part of the story.

Book an Appointment or walk in during store hours. Prefer texting? Reach us at 770-206-8000.

Frequently Asked Questions About Diamond Stud Earrings

What diamond stud size is best for everyday wear?

Most people prefer 0.50–1.00 ctw pairs for a balanced, office-friendly look. Smaller lobes may like 0.33 ctw; larger or thicker lobes can comfortably wear 1.00–2.00 ctw. We fit you in store, so the post that goes through your ear is the right length and the style of back suits you.

Do lab-grown diamond studs look different from natural?

No — both are real diamonds. They have the same hardness, 10 on the Mohs scale, which is the standard scale for how hard a stone is. They bend light the same way, which is what jewelers mean by refractive index, and they sparkle the same. Lab-grown options cost less, so the same budget buys a larger size. Natural diamonds offer geological rarity and timeless, enduring appeal.

Which earring backs are most secure for diamond studs?

We go by size. Under 1.00 ctw, friction backs are quick and low-profile. From 1.00 up to 2.00 ctw, we recommend screw backs. At 2.00 ctw and above, we recommend guardian backs — also sold as La Pousette — both for security and to spread the weight.

What size is a 1 carat diamond stud earring in millimeters?

A 1.00 ctw pair means each stone is approximately 0.50 ct, which measures about 5.2 mm in diameter for a round brilliant cut. This is our "bold everyday" size.

How big is a 4 carat total weight diamond stud earring?

A 4.00 ctw pair means each stone is approximately 2.00 ct, measuring about 8.2 mm in diameter. This creates a dramatic, luxury look. Lab-grown diamonds are what make a 4 ctw pair practical to own.

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Want more detail on diamond types? Read diamonds vs lab vs moissanite, lab-grown vs natural, or our diamond shape guide.