实验室培育钻石

A lab-grown diamond is a diamond. Not a simulant, not a substitute, not "almost". Same carbon lattice, same hardness, same refractive index, same fire. The only difference is where it crystallised. This page explains that properly, and then explains how to actually choose a stone - lab-grown or natural - without overpaying for the wrong thing.

What a lab-grown diamond actually is

Carbon, arranged in the cubic crystal structure that makes a diamond a diamond, grown in a machine over a matter of weeks rather than in the mantle over a matter of aeons.

A gemmologist cannot tell the difference by looking. Neither can a jeweller's loupe, a thermal probe, or your future mother-in-law. Identification requires specialist equipment reading trace growth patterns, which is exactly why every reputable lab-grown stone is laser-inscribed with its report number on the girdle. It is not a secret to be kept; it is a fact to be documented.

What it is not is cubic zirconia or moissanite. Those are different materials that imitate the look of a diamond and behave differently - softer, differently refractive, and they age differently on a hand. We do not sell them.

How they are grown

Two methods, and the one used affects nothing you can see, but it is worth knowing what you are buying.

HPHT - high pressure, high temperature - recreates mantle conditions directly: a carbon source, a metal flux, roughly 1,500 degrees Celsius and pressure in the region of 50,000 atmospheres, around a tiny diamond seed. It is the older method and it tends to produce stones with a slightly different growth structure.

CVD - chemical vapour deposition - is the more common method for gem-quality stones today. A seed sits in a vacuum chamber, methane gas is ionised into plasma, and carbon atoms settle onto the seed layer by layer, growing the crystal upward over several weeks. It gives finer control over purity, which is why most of the very high-clarity lab-grown material you see is CVD.

Either way, what comes out is rough that then goes to a cutter, and is cut exactly as mined rough is cut. The cutting is where the beauty is decided, and it is done by the same hands using the same wheels.

Lab-grown or natural: what actually differs

Four things, and only four.

• Price. The significant one. A lab-grown stone typically costs a fraction of a natural stone of the same size and quality. That difference is the entire practical argument, and it is a strong one: the same budget buys visibly more stone, or the same stone plus a better setting.
• Rarity. A natural diamond is geologically finite and took a billion years. A lab-grown one can be made again next month. If what you want from the object is scarcity, that is a real difference and no amount of chemistry argues it away.
• Resale. Natural diamonds have a thin but functioning secondary market. Lab-grown does not meaningfully have one yet, and prices for new lab-grown stones have fallen steadily as production has scaled. Buy lab-grown because you want to wear it, not because you expect to sell it.
• Environmental footprint. No mining, lower carbon - but dependent on the electricity that grew the stone. We cover this honestly on our sustainability page.

Notice what is not on that list: appearance, durability, hardness, brilliance, how it ages, whether it can be resized or reset, or whether anyone will be able to tell. None of those differ.

The four Cs, in the order that actually matters

They are always listed as cut, colour, clarity, carat, which makes them look equally weighted. They are not. Here is how we rank them at the counter, and why.

1. Cut - this is the whole game

Cut is the only C that is about human skill rather than luck, and it is the one that decides whether a stone looks alive. It describes the angles and proportions the cutter chose: how light enters the crown, bounces off the pavilion facets, and comes back to your eye instead of leaking out of the bottom.

A superbly cut 0.90 carat will out-sparkle a carelessly cut 1.05 in every room you will ever stand in, and cost you less. If you take one thing from this page, take that. We do not sell stones below Excellent or Ideal cut, because a poorly cut diamond is a permanently disappointing object and no setting rescues it.

2. Colour - buy the grade you can see, not the one on paper

Graded D (colourless) down to Z (noticeably tinted). D, E and F are colourless; G through J are near-colourless. The honest guidance: in a white metal setting, most people cannot distinguish G from D once the stone is on a hand, and the price difference between them is substantial.

The exception is metal. Warm metals reflect into a stone - a G or H set in yellow gold reads warmer than the same stone in platinum. If you have your heart set on yellow gold, you can often step down a grade or two and spend the difference on cut or size. If you want platinum and a very white look, go higher.

3. Clarity - the only question is whether you can see it

Clarity grades the tiny inclusions formed as the crystal grew. The scale runs FL and IF (flawless, internally flawless), then VVS1 and VVS2, VS1 and VS2, then SI1 and SI2, then I1 to I3.

The word that matters is eye-clean: no inclusion visible to an unaided eye at normal viewing distance. A VS2 is usually eye-clean and costs meaningfully less than a VVS1 that looks identical on a hand. That is where the value sits, and it is where we buy.

We do not sell SI-grade or cloudy stones at all - not at a discount, not to hit a carat number, not because a report says the grade is acceptable. And we buy stones with no fluorescence, because fluorescence is one of the quiet ways a diamond turns milky in daylight and one of the quiet ways a dealer shaves a price.

4. Carat - weight, not size

Carat measures mass, not the face-up spread you actually see. Two one-carat stones can look noticeably different in width depending on how they were cut - a deep stone hides its weight in the pavilion where nobody admires it.

Two practical notes. Prices step up sharply at the round numbers, so a 0.90 or a 1.90 often looks all but identical to the one above it for a good deal less. And size reads relative to the hand it sits on: bring your actual ring size to the conversation, because the same stone presents very differently at a size 4 and a size 8.

Certification

We do not grade our own diamonds. Nobody credible does.

GIA is the global reference standard and grades both natural and lab-grown stones. IGI is the trade norm for lab-grown reporting and is thorough. AGS is respected, particularly on cut. For rubies and sapphires we work to GRS, where origin and treatment disclosure decide most of the value.

Read the report, not the sticker. Two stones with the same headline grades can differ in ways the summary line hides - polish, symmetry, the position of an inclusion, whether fluorescence is present. Your gemologist will walk you through a report line by line, including the lines that are not flattering.

Choosing a shape

Shape is taste, but each one behaves differently and it is worth knowing how before you fall in love with a picture.

• Round brilliant - fifty-seven facets engineered specifically to return light. The most forgiving shape and the most brilliant, and priced accordingly because more rough is lost cutting it.
• Oval - reads larger than a round of the same weight and elongates the finger. Watch for the bow-tie, a dark band across the centre that poor cutting exaggerates.
• Emerald - step cuts rather than brilliant facets, so it flashes in broad planes instead of sparkling. Architectural and quietly confident, but it hides nothing: clarity and colour must be genuinely good.
• Pear and marquise - dramatic and elongating; both depend entirely on symmetry, and both need a prong protecting the point.
• Cushion - softened corners and a warmer, more romantic scintillation. Very forgiving in candlelight and on older-style settings.
• Princess and radiant - sharp geometry with brilliant faceting. Princess corners are vulnerable and should be protected by the setting.

If it were our money

The advice we give across the counter more than any other, in order:

1. Buy the best cut you can, always. It is the only C you cannot compensate for later.
2. Drop to the lowest colour grade that still looks white to you in the metal you have chosen. Bring the metal to the comparison.
3. Buy eye-clean, not flawless. Nobody has ever admired a ring through a loupe.
4. Step just under the round carat numbers. It is the cheapest size you will ever buy.
5. Then spend what you saved on the setting, because the setting is what you touch every day and what fails first if it is badly made.

Looking after it

Diamond is the hardest natural material there is, which people hear as indestructible. It is not. It is hard, meaning hard to scratch; it can still chip if struck at the wrong angle, and the metal holding it is far softer than the stone.

Take it off for the gym, for gardening, for swimming pools and for anything involving bleach - chlorine attacks the alloys in gold over time. Warm water, a drop of dish soap and a soft toothbrush is all a home clean needs; the film that dulls a diamond is almost always hand cream and skin oil, not damage.

Bring it to us every year or so. We clean it, check the prongs under magnification and re-tip anything that has worn thin, free of charge, for as long as you own it. Stones do not usually fall out suddenly - they fall out after a year of a worn prong nobody looked at.

Still deciding?

Talk to a gemologist rather than reading another page. Every one of our team is GIA-qualified, the conversation costs nothing, and the most useful thing we do is often talk somebody out of the stone they arrived wanting.