Lab-Grown vs. Mined Diamonds: A Fair, Budget-Friendly Guide

A lab-grown diamond is chemically and structurally identical to a mined diamond. Same hardness, same sparkle, same fire. The only real differences are how it was made, what it costs, and the certificate that comes with it.

Lab-grown sits roughly 60-70% below an equivalent mined stone. Both are real diamonds. A jeweller can't tell them apart without specialist equipment. Below is the detail.

How lab-grown diamonds are made

Two methods, both well established:

• HPHT (High Pressure, High Temperature): replicates what happens in the earth's mantle. A small diamond seed is exposed to roughly 1,500°C and 1.5 million PSI in a chamber. Carbon bonds onto the seed and a crystal grows.
• CVD (Chemical Vapour Deposition): a seed is placed in a vacuum chamber filled with carbon-rich gas. The gas ionises, carbon atoms settle on the seed, and the crystal builds up layer by layer.

Both produce a rough crystal that is then cut and polished the same way a mined rough is. We use IGI-certified lab diamonds at Guthrie.

Physical properties: identical

Hardness, refractive index, density, thermal conductivity. All the same. Both are 10 on the Mohs scale. Both pass a diamond tester. Both can be graded on the same 4C scale (Cut, Colour, Clarity, Carat).

The Gemological Institute of America (GIA) and IGI both grade lab-grown diamonds with the same protocols they use for mined stones.

Price

This is the biggest practical difference. A 1ct round brilliant, G colour, VS clarity, ideal cut:

• Lab-grown, IGI certified, in an 18K white gold solitaire at our studio: around $4,000-5,000
• Mined equivalent: around $10,000-14,000

The gap widens at larger sizes. A 2ct lab-grown is around $7,000-9,000; a 2ct mined of the same specs is $25,000+.

Resale and value retention

Honest answer: mined diamonds retain more resale value than lab-grown. Lab-grown prices have dropped year on year as production has scaled, and that trend will likely continue.

That said, the resale market on any diamond is brutal. You typically recover 20-40% of what you paid, mined or lab. If long-term value matters more than the ring on the day, mined holds up better. If it doesn't, lab-grown is the smarter buy.

Environmental and ethical

Lab-grown uses energy, often a lot of it. CVD reactors run hot and long. The footprint depends heavily on the energy source: a lab running on renewables is genuinely low impact; one on coal-fired grid power isn't as clean as the marketing suggests.

Mined diamond impact varies just as much. Modern Australian, Canadian, and Botswanan operations are well-regulated. Stones from conflict regions still find their way through the system despite the Kimberley Process.

Neither is perfect. Lab-grown is generally the lower-impact choice, but it's worth asking where the lab is and where the mine is, rather than assuming.

How to choose

If the budget matters and you want maximum stone for the money: lab-grown.

If tradition, resale, and the idea of a stone formed over a billion years matters: mined.

If you want the diamond look at the lowest price and don't need a certificate: moissanite is worth a look too. A 1ct moissanite ring at our studio runs $1,200-2,500.

What we do at Guthrie

We work with both. IGI certificates on every lab diamond, GIA on most mined stones, hand-made setting in our Southbank studio, 3-6 weeks standard, 3 weeks express for $400. Lifetime stone warranty on every ring.

If you want to see a lab and a mined diamond side by side under daylight, book a studio appointment. Level 7, 80 Dorcas St, Southbank. We also do video consults.