Diamond education,
without the jargon.
Everything you need to choose a diamond with confidence. Written by our master gemmologists, kept up to date as the science and the market evolve.
Cut, color, clarity, carat.
The four universal qualities established by GIA in the 1940s for grading every diamond. Together they describe what you are buying and what it will look like on the finger.
Cut
The most important C
Cut is the only C entirely controlled by human craft, and it determines how a diamond returns light to the eye. A diamond with poor cut will look lifeless no matter how high the color and clarity grade. A diamond with an Excellent or Ideal cut will look brilliant even at lower color grades.
Our recommendation: choose Excellent (GIA) or Ideal (AGS/GCAL). Never settle below Very Good.
Color
D (colorless) to Z (light yellow)
Diamond color grades the absence of color in a white diamond. D, E, and F are considered colorless; G through J are near-colorless. The differences between adjacent grades are subtle and usually invisible to the untrained eye, especially once the stone is set.
Best value: G or H. Indistinguishable from D-F to the unaided eye, 30 to 40% less expensive.
Clarity
FL to I3, measured at 10x magnification
Clarity describes inclusions (internal characteristics) and blemishes (surface marks). It is graded under 10x magnification: a feature invisible to the naked eye still affects the grade. For most buyers, the goal is “eye-clean” - a stone whose inclusions cannot be seen without magnification.
Best value: VS2 to SI1. Eye-clean in 90% of cases, dramatically lower price than VVS.
Carat
1 carat = 0.2 grams = 200 mg
Carat measures weight, not size. Two 1-carat diamonds can look different sizes depending on cut depth and shape (an oval will look larger face-up than a round of the same carat). Diamond prices jump at psychological milestones: 0.50, 0.70, 1.00, 1.50, 2.00 carats. Buying just under a milestone (e.g., 0.95 vs 1.00) can save 10 to 15% with no visible difference.
Prices shown are for 1ct round brilliant lab-grown F/VS1. Naturals run roughly 4-5x higher.
Ten silhouettes.
Round brilliant accounts for roughly seven in ten engagement diamonds sold. The remaining three carry their own personality.
Most popular. Maximum sparkle.
Elongates the finger. Appears larger.
Soft antique-inspired corners.
Step-cut. Elegant, architectural.
Sharp, modern geometric square.
Teardrop. Asymmetrical, romantic.
Elongated boat shape. Vintage.
Brilliant facets in a rectangle.
Step-cut square, art deco.
Romantic. Best at 1ct or above.
Same diamond.
Different origin.
| Property | Lab-Grown | Natural |
|---|---|---|
| Chemical composition | C (carbon) | C (carbon) |
| Hardness (Mohs) | 10 | 10 |
| Refractive index | 2.42 | 2.42 |
| Density | 3.52 g/cm³ | 3.52 g/cm³ |
| Formation time | 2 to 4 weeks | 1 to 3 billion years |
| Formation location | Laboratory (CVD or HPHT) | Earth's mantle, 150-200 km deep |
| Price per carat (1ct F/VS1) | £550 to £1,180 | £3,150 to £4,720 |
| Certification | IGI, GCAL | GIA, IGI, GCAL |
| Resale value | 20 to 30% of retail | 30 to 50% of retail |
| Carbon footprint | ~6 kg CO₂ / ct (renewable energy) | ~57 kg CO₂ / ct (mined) |
| Conflict risk | None | Kimberley Process compliance required |
- You want maximum size and quality for your budget
- Environmental footprint matters to you
- You want a guaranteed conflict-free origin without supply-chain questions
- You prefer a stone whose properties are known to four decimal places
- The romance of geological history matters to you
- You value the stone as an heirloom with long-term resale
- You want to inherit, or pass down, a stone with provenance
- You prefer the well-established trading market for naturals
Who graded your diamond.
An independent grading report is what separates a real diamond purchase from a guess. Here is what each of the major laboratories does and what we recommend.
Founded 1931. The gold standard for natural diamond grading worldwide.
Natural diamond reports and dossiers
Founded 1975. The largest grader of lab-grown diamonds globally.
Lab-grown and natural diamond reports
Founded 2001. Known for light performance and cut grading.
Natural and lab-grown with light performance data
Now operating under GIA. Pioneered the 0-10 cut grading scale.
Historical reports honoured in trade-in valuations
Provenance matters.
Every stone, every time.
Every natural diamond we sell is fully compliant with the Kimberley Process Certification Scheme, ratified by 85 countries to eliminate conflict diamonds from the supply chain. We additionally audit our supplier chain to trace each stone back to mine of origin where possible.
Lab-grown diamonds carry zero conflict risk by definition, plus a substantially lower carbon footprint when produced with renewable energy (we work only with CVD/HPHT growers running on hydro or solar).
Our gold and platinum are 100% recycled and SCS-certified, eliminating the environmental and human cost of fresh metal mining.
Every natural diamond carries documentation of conflict-free origin from a participating country.
Our lab-grown diamond partners run their reactors on hydro or solar. Verified third-party.
100% recycled gold and platinum, certified by Scientific Certification Systems.
A diamond, kept brilliant.
Diamonds attract oils and lotions, which dull their light return. A simple home routine keeps your piece looking new. Bring it to us once a year for free professional cleaning and a four-point setting inspection.
- 01Weekly: warm-water bathMix a few drops of dish soap into warm water. Soak the piece for 20 to 30 minutes, brush gently behind the stone with a soft toothbrush, rinse, pat dry.
- 02Avoid: chlorine, harsh chemicals, abrasivesRemove rings before pool, gym, and using cleaning products. Chlorine can pit gold prongs over time.
- 03Store: separately, in soft pouchesA diamond can scratch any other gemstone. Store each piece in its own pouch or compartment.
- 04Annually: bring in for inspectionProngs wear over decades. A 10-minute inspection catches loose stones before they are lost. Complimentary for life.
Plain answers.
Which C is the most important of the 4Cs?
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Cut is the most important C. A poorly cut diamond will look dull regardless of color or clarity. After cut, prioritise carat if size matters most, color (G to H for the best price-to-eye-appeal ratio), and clarity last (VS2 to SI1 are typically eye-clean and offer the best value).
Are lab-grown diamonds real diamonds?
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Yes. Lab-grown diamonds are chemically, physically, and optically identical to natural diamonds. Both are pure crystallized carbon (sp3 bonded). The Federal Trade Commission (FTC), GIA, and IGI all recognize lab-grown stones as real diamonds. The only difference is origin: natural diamonds form in the earth over billions of years, while lab-grown diamonds form in a laboratory in a few weeks using either CVD or HPHT methods.
How much should I spend on an engagement ring?
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There is no rule. The "two months salary" guideline was a 1930s De Beers marketing slogan, not a real benchmark. Spend what feels right to you. Many of our most-loved engagement rings sit between £2,400 and £6,500. Lab-grown diamonds make a 1.5 to 2 carat solitaire achievable in that range. For naturals, similar designs typically start at £9,500.
What is the difference between GIA and IGI certification?
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Both are respected independent gemological laboratories. GIA (founded 1931) is the long-established standard and grades primarily natural diamonds. IGI (founded 1975) has become the dominant grader of lab-grown diamonds. GIA grading tends to be incrementally stricter than IGI on color and clarity by roughly half a grade. For a like-for-like comparison, factor that in when comparing prices across reports.
How do I know my diamond is conflict-free?
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All natural diamonds at Buy Fine Diamonds are Kimberley Process certified and traced through audited supply chains back to mine of origin where possible (Botswana, Canada, Russia, Australia). Lab-grown diamonds have zero risk of conflict origin and a substantially smaller environmental footprint. Our metals are SCS-certified recycled gold and platinum.
What does laser inscription mean?
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Most certified diamonds carry a microscopic inscription on the girdle (the thinnest edge of the stone) showing the certificate number. The inscription is invisible to the naked eye but verifiable under 10x magnification. It is a permanent way to confirm that the physical stone matches its paper certificate.
Will a lab-grown diamond hold its value?
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All diamonds depreciate from retail to secondary market. Natural diamonds typically retain 30 to 50% of retail value on resale; lab-grown diamonds resell for less because production cost has fallen quickly. For this reason, view a diamond purchase as an emotional and design decision, not an investment. We offer a lifetime upgrade program that credits 100% of your original purchase toward a future diamond of higher value.
How do I find my ring size?
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Three options: (1) order our complimentary ring sizer kit (ships free, 2 to 3 days), (2) measure an existing ring against our printable size guide at /education/ring-size-guide, or (3) visit a local jeweller for a free sizing. Avoid measuring at the end of a hot day or after exercise when fingers swell. We offer free resizing within the first year.
Still deciding?
Book a free virtual consultation. Bring your budget and your taste. We will bring the stones to choose from and the answers to every question you have not yet thought to ask.