Natural · Laboratory grown
Two origins. One carbon.
We set both, and we say which is which. A diamond is a technical object before it is a symbol: it is described, graded and certified. This page explains how.
Crystallised one to three billion years ago, more than a hundred and fifty kilometres below the surface, then carried up by kimberlite pipes. Mined, cut, graded.
An international price index and an established resale value. Each stone carries inclusions that identify it the way a fingerprint does — they are drawn on the report.
Graded by the GIA
Pure carbon crystallised in a few weeks, by chemical vapour deposition (CVD) or under high pressure and high temperature (HPHT). Same composition, same hardness, same refractive index — the same stone, grown differently.
At equal characteristics, a fraction of the price: the carat you were weighing up becomes the carat you can have. The market is recent, so resale value stays low — we say so before you buy.
Graded by the IGI
The report states Laboratory Grown, and the words are laser-inscribed on the girdle of the stone.
The nature of the stone is written on the label, on the invoice and on the certificate. Never in small print.
The grading
Carat, colour, clarity, cut. Four letters that fix the price of a stone — the same four for a natural diamond and for a laboratory-grown one.
One carat is exactly 0.20 gram. Price does not follow weight in a straight line: it jumps at every round figure, because large stones are rare. A one-carat stone is worth far more than two half-carat stones.
The GIA scale runs from D, exceptional white, to Z, tinted. D to F is colourless; G to J still looks colourless to the naked eye. The least understood price gap sits between those two groups.
The number, size and position of the inclusions, seen under a ten-times loupe. From IF, flawless, to P3. The laboratory draws their map on the report: that page identifies your stone, and no other.
Proportions, angles, polish. It is the only one of the four that depends entirely on the cutter's hand — and the only one that decides whether the stone gives the light back or keeps it. A fine diamond badly cut stays dark.
Photographs of the four criteria: Gemological Institute of America.
Certification
The stone is graded by an independent laboratory that neither owns it nor sells it. Here is one of ours — an actual report, for an actual stone.
What to read on it
A report carries a number, and that number can be checked by anyone, directly with the laboratory, in a few seconds. Here are the two addresses.
GIA
Gemological Institute of America
Film: Gemological Institute of America — The 4Cs: Cut, 1 min 25, in English.
Founded in 1931. The GIA invented the 4Cs and the D-to-Z colour scale that the whole trade now uses. It is the reference for natural diamonds, and the laboratory whose reports hold their value best on the second-hand market.
What the report carries
IGI
International Gemological Institute
Film: International Gemological Institute — IGI explains Lab Grown Diamonds, 1 min 42, in English.
Founded in Antwerp in 1975. The IGI is the laboratory that grades the great majority of the laboratory-grown diamonds in circulation. Its report states the growth method — CVD or HPHT — and never lets the stone pass for a mined one.
What the report carries
The workshop
Thirty-one years at the bench — Boulle, Cartier high jewellery, Montreal, New York. A report is a document; the loupe is the moment you understand what you are buying.
Natural on one side, laboratory grown on the other, under the same light. Then you choose.
Choose the mount, choose the stone.