Laboratory-grown diamonds
How a laboratory-grown diamond is made
A laboratory-grown diamond is diamond. Same carbon, same crystal lattice, same hardness, same way of handling light. What changes is where it grew. Here is the sequence, plainly.
Step 1: Seed
A wafer of diamond about the size of a fingernail goes into the growth chamber. Every stone begins on a piece of another diamond.
Step 2: Growth
Carbon-rich gas is heated until carbon atoms release and settle onto the seed, layer by layer. A stone of a useful size takes several weeks.
Step 3: Cutting
The rough goes to the bench. It is sawn, bruted, faceted and polished exactly the way mined rough is, by the same cutters, with the same tools.
Step 4: Grading
The polished stone goes to an independent laboratory, which grades it for cut, colour, clarity and carat and issues a report under a number that is usually laser-inscribed on the girdle.
There is a second method, HPHT, which reproduces the pressure and heat found deep underground instead of growing the stone from gas. Both produce the same material. Which one a stone came from is recorded on its report; it does not change what you are looking at.
Reading a stone
The words on a grading report
Eight terms do almost all of the work. Once you know what each one is actually measuring, you can read any report yourself and decide what is worth paying for.
Cut
Cut is the only one of the four Cs that is entirely human. It measures how well the stone was proportioned and finished: the angle of the facets, how evenly they meet, how flat the table sits, how clean the polish is.
Two stones with identical colour, clarity and weight can look like different objects because of it. Cut is graded Excellent, Very Good, Good, Fair, Poor.
If you read one line on a report, read this one. A well-cut stone at a lower colour grade will out-perform a badly cut stone at a higher one, every single time.
Colour
Colour grades how little colour a stone has. The scale runs from D, at the colourless end, down to Z.
D to F is colourless. G to J is near-colourless, and once a stone is set, the difference is very hard to see. Below that a warm tint starts to show, and it shows most against white metal.
Yellow gold flatters the warmer grades. In a yellow-gold setting, G to J reads no differently to F on the hand, and costs less to get there.
Clarity
Clarity records what is inside the stone and what is on its surface: tiny crystals, feathers, clouds, marks left from polishing.
FL and IF are flawless. VVS and VS inclusions need magnification to find. SI can occasionally be caught by a careful eye. I is visible without help.
Eye-clean is the threshold that matters, not flawless. VS and better is eye-clean in almost every case, and a good SI1 very often is too.
Carat
Carat is weight, not size. One carat is 0.20 grams.
Two stones of the same weight can face up quite differently depending on how deep they were cut, which is why the millimetre measurement printed on a report is often more useful to you than the carat figure.
Prices step up sharply at round numbers. A 0.90 ct stone costs meaningfully less than a 1.00 ct one and is roughly a third of a millimetre smaller across the top.
Brilliance
The white light a stone sends back to your eye. Light enters through the table, bounces off the internal facets, and leaves through the top.
If the angles are wrong, light escapes out of the bottom instead of returning. That is the flat, glassy look you sometimes see in a stone that reads well on paper.
Judge a stone under a plain ceiling light, not a jeweller's spotlight. Everything looks alive under a spotlight.
Fire
The coloured flashes. White light splits into its spectrum as it passes through the stone, the same way it does through a prism.
Smaller tables and steeper crown angles generally give more of it, which is why some older cuts throw more colour than a modern round.
Fire shows best in dim light from a single source. Candlelight is the honest test.
Scintillation
The sparkle that only appears when something moves — the stone, your hand, or you.
It is the pattern of facets catching and losing the light in turn. A stone with good scintillation stays interesting across a whole evening rather than in one photograph.
Move the piece. Do not stare at it. A stone that only looks good held still is not a stone you will enjoy wearing.
The report
An independent laboratory report — IGI or GIA — records the four Cs, the measurements, the proportions and the growth method, under a number that is usually laser-inscribed on the girdle of the stone.
It is a description, not a valuation. Nothing on it tells you what a piece should cost.
Check that the number on the report matches the inscription on the stone. Any jeweller can show you that under a loupe in ten seconds, and should offer before you ask.
Nothing on this page is specific to ORIVA. It is how the trade grades stones, written out so that you walk into any shop knowing what the person behind the counter knows.
