Lab-grown blue diamonds: as-grown color, explained

Most blue diamonds on the market — mined or grown — were not born blue. Ours are. This page explains what makes a laboratory-grown diamond blue, why that is the hardest color to grow, how to read a grading report for one, and what a blue diamond honestly costs. It is written by the people who make them, from inside the factory where they grow.

What is a lab-grown blue diamond?

A laboratory-grown blue diamond is a real diamond — carbon, crystallized in the same cubic lattice as any mined stone — whose blue color comes from trace atoms of boron caught inside the crystal as it grows. Boron sits next to carbon on the periodic table. When a boron atom takes a carbon atom's place in the lattice, it absorbs red light, and the stone reads blue. The famous mined blues, including the Hope Diamond, are blue for exactly the same reason.

Diamonds with boron in the lattice are classed as type IIb — among the rarest categories of diamond in existence, mined or grown. They have a property no other diamond has: they conduct electricity. A blue diamond is, technically, a semiconductor. The same material grown for us is grown, in other forms, for quantum sensors and high-power electronics.

A blue diamond is blue all the way through its chemistry, not on its surface. Cut it in half and both halves are blue.

As-grown blue vs. treated blue — the question to ask before buying

There are two ways a diamond ends up blue, and sellers are not always eager to explain the difference.

• As-grown color: boron is introduced during growth, and the crystal comes out of the reactor blue. Nothing is done to the stone afterward except cutting and polishing.
• Treated color: a colorless or brownish diamond is irradiated, and sometimes heated, after growth to change its color. This is common, legal, and must be disclosed — but it is a different thing, and grading reports say so.

Blue is the hardest color to achieve as-grown. Boron only incorporates cleanly under tightly controlled conditions, which is why genuinely as-grown blue material is scarce even among laboratory growers. Every blue diamond we sell is as-grown, and its grading report states the color origin. If you are buying a blue diamond anywhere — including from us — ask for the report line that says where the color came from. A seller who cannot show it is asking you to take color on faith.

How a blue diamond grows

Our stones begin as a diamond seed: a thin, flat wafer of diamond a few millimetres across. In an HPHT press, the seed sits beneath a metal solvent and a carbon source at pressures above 50,000 atmospheres and temperatures around 1,400 °C — conditions borrowed from the Earth's mantle. Carbon dissolves, migrates, and crystallizes onto the seed, atom by atom, with boron metered into the chemistry. Growing a stone worth cutting takes weeks, and blue takes longer to get right than any color we grow.

The rough crystal that emerges looks nothing like jewelry. It is cut, faceted and polished by hand — in our case by named craftspeople in our family factory in Dubai, the same people who then set it. We document this process rather than describe it; you can watch a numbered stone travel from seed to finished piece on our journal.

How lab-grown blue diamonds are graded

Colored diamonds — called fancy color diamonds — are graded on different terms than white ones. Instead of the D-to-Z letter scale, a fancy color grade describes hue, tone and saturation: Fancy Light Blue, Fancy Blue, Fancy Intense Blue, Fancy Vivid Blue. Depth of color, not absence of it, is the point.

Our stones are graded by IGI, the leading laboratory for grown diamonds, under its Laboratory-Grown Fancy Colored Diamond Report. The report states that the stone is laboratory-grown, its fancy color grade, and the origin of its color. Every piece we sell ships with its report. We consider the document part of the object.

What does a blue diamond cost?

Stated plainly, once: mined blue diamonds are among the most expensive objects per gram that human beings trade — fine vivid blues have sold at auction for over a million dollars per carat. That is a fact about geology and scarcity, not a measure of beauty, and it is not why our pieces are priced as they are.

Our prices are set by what a piece costs to make well: weeks of growth, hand-cutting, precious metal, setting by named craftspeople, and independent grading. Pieces at State of Matter range from about €3,300 to €38,000, blue included. We do not price the color's mythology. We price the work.

Blue diamond jewelry: how we make ours

Every design in our collection is made to order in four as-grown colors — blue, pink, yellow and green — in your size, typically within four to six weeks. Blue is where we began: our first documented stone, grown from seed on camera, finishes as a blue bangle. If you want to see a blue diamond ring or bangle in person before commissioning one, our Stockholm appointments open this autumn.

Common questions

Are lab-grown blue diamonds real diamonds?

Yes. They are carbon in a diamond lattice, with the same hardness (10 on the Mohs scale), the same brilliance, and the same optical behavior as mined diamonds. The honest difference is origin — weeks in a reactor rather than a billion years underground — and we state it in full everywhere: laboratory-grown diamond.

Will the blue fade?

No. The color is boron in the crystal lattice — part of the stone's atomic structure. It cannot fade, wash out or wear off, and it needs no special care.

Is a blue lab-grown diamond good for an engagement ring?

Mechanically it is identical to any diamond, which is to say: the hardest material you can set in a ring. Whether the color suits an engagement ring is a question of taste, and we are partial.

How can I verify the color is as-grown?

Read the grading report. IGI fancy color reports state color origin. Ours ship with every piece, and we publish what to look for — the closer you look, the more you see.