01
Carat
The weight of the diamond — 1 carat equals 200 milligrams. Two diamonds of the same carat can look very different depending on their cut and shape.
Tip: A well-cut 0.90ct stone often appears larger than a poorly cut 1.00ct stone.
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Diamond education
Know what you’re buying.
A plain-English guide to the 4Cs, shapes, and certifications that define every Stone Theory diamond.
Chapter 01
The 4Cs
Carat, Color, Clarity, and Cut are the four objective measures that define a diamond's quality and value. Understand these, and you can read any certificate.
02
Color
Graded D (absolutely colorless) through Z (light yellow). Most customers are happiest in the G–H range — near-colorless with significant value over D.
Tip: Yellow-gold settings mask slight warmth, so H–J can look perfect mounted.
03
Clarity
Ranges from Flawless (FL) down to Included (I). VS1–VS2 stones are "eye-clean" — inclusions only visible under 10× magnification.
Tip: Clarity above VS2 rarely affects how the diamond looks to the naked eye.
04
Cut
How well the diamond's proportions reflect light. Rated Poor to Excellent (or Ideal). Cut has the biggest impact on brilliance — prioritize it over size.
Tip: Don't compromise on cut. An Excellent-cut 1ct will outshine a Good-cut 1.5ct every time.
Chapter 02
Find your shape
Shape is the first decision, and it changes how a diamond sparkles, how large it looks, and how it wears. Choose a shape below to see how it behaves, then shop it.
Round
The classic. Maximum fire.
- Cut style
- Brilliant
- How it sparkles
- Fireworks: the most light return of any shape
- Length-to-width
- 1.00 (a perfect circle)
- Looks great in
- Solitaire, halo, three-stone. It suits every setting.
Good to know: Round diamonds usually cost the most per carat, because more of the rough crystal is lost when it is cut. They also hide small inclusions and tint well, so you can often drop a color or clarity grade without seeing a difference.
Shop Round diamonds
Oval
Flattering, with round-level sparkle.
- Cut style
- Brilliant
- How it sparkles
- Fireworks in an elongated shape
- Length-to-width
- 1.30 to 1.50
- Looks great in
- Solitaire, hidden halo, three-stone.
Good to know: An oval looks larger than a round of the same carat weight and lengthens the finger. Check for a "bow-tie", a darker band across the middle, in the photos or video.
Shop Oval diamonds
Cushion
Soft, romantic, a little vintage.
- Cut style
- Brilliant
- How it sparkles
- Pillowy flashes, like crushed ice
- Length-to-width
- 1.00 to 1.20
- Looks great in
- Halo and vintage settings.
Good to know: Cushion cuts come in "chunky" and "crushed ice" facet styles, so look at the stone itself. Rounded corners make them a durable everyday choice.
Shop Cushion diamonds
Emerald
Quiet, architectural, elegant.
- Cut style
- Step cut
- How it sparkles
- Mirror-like flashes, not fireworks
- Length-to-width
- 1.30 to 1.50
- Looks great in
- Solitaire, three-stone, or a bezel.
Good to know: Long step facets act like a window into the stone, so clarity shows. Choose VS1 or better, and make sure the stone is cut well. Its long lines make the finger look slender.
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Pear
Romantic, distinctive, in between.
- Cut style
- Brilliant
- How it sparkles
- Round-style sparkle with a graceful point
- Length-to-width
- 1.50 to 1.75
- Looks great in
- Solitaire or halo.
Good to know: A pear combines a round end with a point. Wear it point-up or point-down to suit you. Like the oval and the marquise, it can show a bow-tie, so compare stones carefully.
Shop Pear diamonds
Princess
Sharp, modern, geometric.
- Cut style
- Brilliant
- How it sparkles
- Bright, sharp-edged sparkle
- Length-to-width
- 1.00 to 1.05
- Looks great in
- Solitaire with V-prongs, or a bezel.
Good to know: The corners are the weak point, so a setting that covers them matters. Princess cuts make good use of the rough crystal, which often means a better price per carat than round.
Shop Princess diamonds
Radiant
Rectangular shape, brilliant fire.
- Cut style
- Brilliant (rectangular)
- How it sparkles
- Lively, layered sparkle
- Length-to-width
- 1.20 to 1.40
- Looks great in
- Solitaire or three-stone.
Good to know: The trimmed corners make this one of the most chip-resistant fancy shapes. It gives a rectangular silhouette with much more sparkle than an emerald, and hides inclusions well.
Shop Radiant diamonds
Marquise
Regal, long, rare.
- Cut style
- Brilliant
- How it sparkles
- Dramatic sparkle across a long shape
- Length-to-width
- 1.75 to 2.15
- Looks great in
- Solitaire or vintage settings.
Good to know: The marquise has the largest look per carat of any shape. Its two points are delicate, so choose a setting that protects them. A bow-tie is common, so compare stones.
Shop Marquise diamonds
Asscher
Art Deco glamour.
- Cut style
- Step cut
- How it sparkles
- Hall-of-mirrors flashes in an X pattern
- Length-to-width
- 1.00 to 1.05
- Looks great in
- Vintage and Art Deco settings.
Good to know: Like the emerald, the Asscher is a step cut that shows clarity, so choose VS1 or better. Its square outline and cut corners give a look that stands apart from rounds.
Shop Asscher diamonds
Heart
The romantic statement.
- Cut style
- Brilliant
- How it sparkles
- Bright, playful sparkle with a romantic outline
- Length-to-width
- 0.90 to 1.10
- Looks great in
- Solitaire or pendant-style settings.
Good to know: The heart is the most symbolic shape and shows best in larger stones, about 1 carat or more, where the cleft is clear. Choose a setting with a protective prong at the point and the cleft.
Shop Heart diamonds
Chapter 03
Independent certification
Every Stone Theory diamond is graded by an independent laboratory. The certificate is your receipt of quality — nobody can fudge it.
GIA
Gemological Institute of America
Founded in 1931, GIA set the 4C grading standard used worldwide. The most rigorous and conservative grading body.
IGI
International Gemological Institute
The largest independent gemological laboratory. Trusted worldwide for consistent, precise grading of lab-grown diamonds.
Every certificate we issue is included with your purchase and linked from your order page. You can verify any of them directly with the issuing lab.
Chapter 04
Our diamonds
Stone Theory sells exclusively lab-grown diamonds — chemically, physically, and optically identical to mined diamonds, but with cleaner origins and a price that lets you wear something extraordinary.
Why lab-grown
- Identical to mined diamonds at the atomic level — same hardness, same fire, same brilliance
- Grown in weeks under controlled conditions, not extracted from the earth
- Significantly more accessible at the same spec, so you can choose a larger or higher-grade stone
- Zero mining impact and a transparent, traceable supply chain
- Independently graded by IGI or GIA on the same 4C scale used for mined diamonds
Lab-grown vs. natural
- What they are: Both are real diamonds made of crystallized carbon. The difference is where they grow, not what they are.
- Origin: Natural diamonds formed deep in the earth over billions of years. Lab-grown diamonds crystallize in a controlled environment in a matter of weeks.
- Price: At the same carat, color, clarity and cut, lab-grown typically costs far less, so the same budget buys a larger or higher-grade stone.
- Resale value: Natural diamonds have historically held more resale value. Lab-grown diamonds generally resell for much less, so they suit buyers who want to wear and enjoy the stone.
- Grading: Both are graded on the same 4C scale. Lab-grown reports state clearly that the stone is laboratory-grown.
- Telling them apart: Not by eye. Only specialized lab equipment can separate the two, which is why every lab-grown stone carries a laser-inscribed serial number.
Every Stone Theory diamond ships with its independent grading report and a unique laser-inscribed serial number you can verify directly with the issuing lab.
Ready to find yours?
Our craft
Made by hand, made to keep.
Each Stone Theory ring is made to order in our studio from solid recycled gold or platinum, with conflict-free lab-grown diamonds certified by IGI or GIA.
Fully online, shipped fully insured, and backed by a guarantee each time.