Are Lab Grown Diamonds Real Diamonds?

This is the first question almost everyone asks, and it deserves a straight answer: a lab grown diamond is a real diamond. Not a simulant, not a lookalike, not "almost" a diamond. It is carbon arranged in the same cubic crystal structure, with the same hardness, the same refractive index and the same optical behaviour as a stone pulled out of the ground.

What differs is where it formed and how long it took.

What a diamond actually is

A diamond is pure carbon whose atoms have locked into a rigid cubic lattice under extreme pressure and heat. That lattice is what gives diamond its defining properties — a hardness of 10 on the Mohs scale, a refractive index of about 2.42, and the way it bends and returns light.

Nothing in that definition says anything about geography. A carbon lattice grown in a reactor in twelve weeks is the same material as one grown 150km below the earth's surface over a billion years. Under a microscope, under a spectrometer, on a hardness test — it behaves identically.

In the United States, the Federal Trade Commission updated its jewellery guidelines in 2018 to remove "natural" from the definition of a diamond, precisely because lab grown stones are diamonds by every material measure.

How they are grown

There are two production methods, and both start with a thin slice of diamond called a seed.

HPHT — High Pressure, High Temperature

This method recreates the conditions found deep in the earth's mantle. The seed is placed with pure carbon in a press that applies roughly 1.5 million pounds per square inch at temperatures around 1,500°C. The carbon dissolves and crystallises onto the seed, layer by layer.

CVD — Chemical Vapour Deposition

The seed sits in a sealed chamber filled with carbon-rich gas, usually methane. The gas is heated until it ionises into plasma, breaking the molecular bonds. Carbon atoms rain down onto the seed and bond to the existing lattice. The crystal grows upward in flat layers.

CVD is the more common method for gem-quality stones today. It runs at lower pressure and gives growers finer control over the result.

How they are graded

Exactly like mined diamonds — on the same 4Cs, by the same laboratories, using the same scales.

Our lab grown diamonds are certified by IGI. A certificate records cut, colour, clarity and carat weight, plus measurements, proportions and any fluorescence. It also states plainly that the stone is laboratory grown, and most stones carry a laser inscription on the girdle recording the report number.

There is no separate, softer grading scale for lab grown stones. A G colour, VS1 clarity lab grown diamond has been assessed against the same standard as a mined stone with those grades.

Where they genuinely differ

Three real differences are worth knowing.

Price

This is the big one. A lab grown diamond typically costs a fraction of a mined diamond of comparable size and quality. The saving is not a compromise in the stone — it reflects a supply chain measured in weeks rather than geological time, without mining, and with far fewer hands between the reactor and the ring.

Practically, this means the budget that buys a well-cut 1 carat mined stone will often buy a noticeably larger or higher-graded lab grown one.

Origin, and what it means for resale

Mined diamonds carry a scarcity story that lab grown stones do not. If your reason for buying is investment or resale, understand that neither mined nor lab grown diamonds are reliable investments — retail jewellery of any kind sells at a significant loss second-hand. But lab grown stones have less established resale infrastructure, and prices have fallen as production has scaled.

Buy a lab grown diamond because you want to wear it. That is the honest case for it.

Trace growth characteristics

A trained gemmologist with the right equipment can identify a lab grown diamond by its growth patterns, strain signature or trace elements. This requires specialist instruments — it is not something visible to the eye, a loupe, or a handheld diamond tester, which will read a lab grown stone as diamond because it is one.

What lab grown diamonds are not

It is worth separating them clearly from simulants, which are different materials that resemble diamond:

• Cubic zirconia — zirconium dioxide. Hardness 8.5, noticeably less brilliant, clouds and scratches with wear.
• White sapphire — aluminium oxide. Hardness 9, but low dispersion, so it reads glassy rather than fiery.
• Moissanite — silicon carbide. Hardness 9.25, and genuinely beautiful, but a different stone with its own distinct look. We stock it deliberately, and we call it what it is.

None of these are diamonds. A lab grown diamond is.

The short version

If someone hands you a lab grown diamond and a mined diamond of identical grade, you cannot tell them apart — not by eye, not by loupe, not by a jeweller's tester. They are the same material, graded on the same scale, certified by the same labs.

The difference is the price, the origin, and how you feel about each. All three are yours to weigh.