Lab Grown and Mined Diamonds: The Honest Comparison

This is the question underneath most diamond buying now, and it deserves a straight answer rather than a pitch in either direction. We sell lab grown, which is a reason to be careful about what we claim.

What is genuinely the same

The fourth row surprises people. A standard diamond tester measures thermal conductivity, which is a property of the material rather than its origin — so it cannot distinguish the two. Identifying a lab grown stone requires specialist laboratory equipment, which is exactly why reputable labs inscribe them.

How they are made, briefly

HPHT reproduces the pressure and temperature conditions of natural formation, using a metal flux; stones grown this way sometimes contain tiny metallic inclusions and can occasionally show a magnetic response.

CVD grows the crystal from carbon-rich gas at lower pressure, layer by layer; inclusions here tend to be graphitic rather than metallic.

For a finished, graded stone this matters less than it sounds. A stone is graded on what it is, not how it was made — so the growth method is a fact about the stone rather than a quality tier, and it should not by itself drive the decision.

What changed in grading

Worth knowing because it affects how you compare reports. GIA moved to Premium and Standard descriptors for lab grown stones on 1 October 2025, while IGI and GCAL continue to issue full 4Cs.

The practical consequence: a GIA lab grown report and an IGI one cannot be lined up cell by cell, and a stone with a GIA report will not show the same detail. Neither is better; they are different documents. If you want the full grading detail on a lab grown stone, that currently means IGI or GCAL.

Where each one makes sense

Lab grown suits you if visible size or specification at a given budget is the priority, or if you would rather put the difference into construction — a thicker shank, a platinum head, a better setting — than into the stone. It is also the straightforward choice if you find the price of the mined equivalent hard to justify for what is, materially, the same thing.

Mined suits you if origin genuinely matters to you — and that is a legitimate reason that needs no defending — or if resale value forms part of how you think about the purchase, or if the piece is meant to sit alongside inherited stones of known provenance.

What should not decide it: claims that one sparkles more, one is harder, or one is “real”. Those are marketing positions rather than physical differences.

If you choose lab grown, spend it here

1. Cut, always. Production clusters at high colour and clarity, so cut is the only C genuinely separating stones. Excellent or Ideal, with polish and symmetry both Excellent or Very Good.
2. Just under a round weight. 0.90 ct measures 6.2 mm against 6.5 mm at 1.00 — the round numbers are price thresholds, not size ones.
3. Eye-clean, not high clarity. Below a carat, SI1 is usually invisible — and the plot diagram matters more than the grade, since position beats grade.
4. Colour matched to the metal. G–H reads white in warm gold. Paying for D in yellow gold is paying for something the setting removes.
5. The construction. A 1.8–2 mm shank and a properly built head outlast any grade decision you make.

And one honest boundary

Below roughly 0.30 ct per stone, the case for lab grown diamond thins considerably. Melee under about 0.20 ct is never individually certified in any material, so the documentation advantage disappears — and at three or four millimetres, a well-cut moissanite is not something anyone distinguishes in wear.

So for pavé, small studs, tennis bracelets and eternity rows, moissanite is the more efficient purchase. We make both and would rather say that than sell you the dearer one for no visible gain.

Frequently asked questions