What is the same
A lab-grown diamond and a natural diamond are both diamond: carbon atoms locked in the same cubic crystal. Every property that can be measured on the finished stone is shared.
- Material
- Carbon
- Hardness
- 10 on the Mohs scale
- Refractive index
- 2.42
- Dispersion
- 0.044
- Density
- 3.52 grams per cubic centimetre
- Graded on
- Cut, colour, clarity, carat
They are cut by the same cutters, set in the same way and worn for the same lifetime. In 2018 the United States Federal Trade Commission removed the word "natural" from its definition of a diamond for this reason.
What is different
The difference is history, and what follows from it.
| Difference | Lab-grown diamond | Natural diamond |
|---|---|---|
| Origin | Grown in a laboratory in a few weeks | Formed more than 150 kilometres below the surface, over 1 to 3 billion years |
| Supply | Grown to meet demand | Finite, and mined |
| Price | Considerably lower for the same grades | Higher, and it rises steeply with size |
| Resale | Lower than a natural diamond | Lower than its retail price |
| Grading report | States that the stone is laboratory-grown | States that the stone is natural |
| Inscription on the girdle | The report number and the words laboratory-grown | The report number, when the stone is inscribed |
How they are told apart
Not by eye, and not with a jeweler's loupe. A standard diamond tester reads both as diamond, because both carry heat in the same way.
A gemmological laboratory separates them with instruments. Most lab-grown diamonds are type IIa, a very pure kind of diamond with almost no nitrogen, which fewer than two in a hundred mined diamonds are. Screening devices look for that first. Spectroscopy and ultraviolet imaging then read the way the crystal grew. An HPHT crystal grows as cubes and octahedra together, a CVD crystal in flat layers, and a diamond in the earth as an octahedron. The three patterns do not match.
For a buyer the answer is simpler. Read the grading report, and match the number inscribed on the girdle to it.
Price and resale
A lab-grown diamond costs considerably less than a natural diamond of the same cut, colour, clarity and carat. It carries no cost of mining, and it can be grown to meet demand.
The gap widens with size. Large natural crystals are rare, so the price of a natural diamond climbs steeply with every carat. A lab-grown diamond climbs more gently. That is why the same budget usually reaches a larger or better cut lab-grown stone.
Be clear about resale. Most diamonds resell for less than their retail price, and a lab-grown diamond currently resells for less than a natural one. Buy a diamond to wear it.
Origin, mining and energy
A natural diamond is mined, which means moved earth, and its path from the mine to the ring passes through many hands. The Kimberley Process, an agreement between governments, certifies rough diamonds as free from conflict. It does not cover every question a buyer may have about a mine.
A lab-grown diamond has no mine, and its origin is known from the first day. Growing it takes a great deal of electricity, so its footprint depends on the energy the grower uses. We would rather say that plainly than call any diamond green.
Which to choose
- Choose a lab-grown diamond if you want the largest or best cut stone your budget allows, if a known origin matters to you, and if you are buying it to wear.
- Choose a natural diamond if the age and rarity of a stone formed in the earth matter to you, or if you place weight on what it may resell for.
Neither choice is wrong, and no one who sees the ring will know which you made.
ART works only with lab-grown diamonds. Read lab-grown diamonds, explained, or see the engagement rings.
