Lab-Grown Diamond Education for NZ Jewellers

01Origin

How a lab-grown diamond is made.

Two methods — over six to eight weeks in a controlled chamber. A diamond seed, a carbon source, energy. The result is the same crystal lattice, the same hardness, the same brilliance. The only thing missing is the mine.

METHOD · CVD Chemical Vapour Deposition

Carbon-rich gas is ionised in a vacuum chamber; carbon atoms settle onto the seed layer by layer, growing the crystal upward.

METHOD · HPHT High Pressure High Temperature

The seed and carbon source are subjected to conditions mirroring the earth's mantle — the carbon crystallises around the seed.

Macro photograph of a lab-grown diamond's facets — Facet structure · identical crystal lattice to mined

WATCH · 2 MIN 15 SEC

From carbon seed to certified diamond — the CVD and HPHT growth process, explained. Every Nuriel stone is grown using one of these two methods and certified by IGI before it enters our vault.

02Grading

The 4Cs, identically applied.

Lab-grown diamonds are graded on the same scales as mined — by the same labs. Nuriel uses IGI, the specialist for lab-grown reports. Every stone is laser-inscribed with its report number on the girdle, so it's verifiable for the life of the stone.

C · 01

Carat

Weight, not size — though the two track closely within a shape. Oval and pear spread larger per carat; deep-cut stones face up smaller.

C · 02

Colour

Graded from D (colourless) downward. To the naked eye, G–H is indistinguishable from D–E in most settings.

DEFGHIJK

Nuriel stocked range · D–H

C · 03

Clarity

Inclusions under 10× magnification. VS1–VS2 is reliably eye-clean across all shapes and sizes.

FLIFVVS1VVS2VS1VS2SI1SI2

Nuriel stocked range · VVS1–VS2

C · 04

Cut

The one C that people, not nature, control — and the biggest driver of brilliance. We stock Excellent cut as the baseline.

Diamond proportion diagram — table, depth, crown and pavilion angles

03Value & stock

The compromise you no longer have to make.

Selling a mined diamond is triage. The budget arrives first and the stone is assembled backwards from it — size, or colour, or clarity, or cut, and the client rarely gets all four. Lab-grown removes the arithmetic that forces the choice. At our trade prices the client can hold top colour, eye-clean-and-beyond clarity, an Ideal cut and the carat they came in for, in the same stone. That is not a cheaper diamond. It is the stone at the top of the chart, which most clients have never been offered.

	D	E	F	G	H
VVS1	●	●	●	●	●
VVS2	●	●	●	●	●
VS1	●	●	●	●	●
VS2	●	●	●	●	●
SI1

Where we buy · D–F × VVS1–VS1 Also stocked · to H, to VS2

Of the stones held in Auckland today, 17 of 20 are D–F and every round is IGI Ideal cut. We buy to the top of the chart because at these prices there is no reason to buy anywhere else — and because a jeweller who can say “D colour, VVS, Ideal cut” is selling a better stone, not a cheaper one.

04Fancy shapes

There is no cut grade on an oval. Here is what to read instead.

IGI grades cut on round brilliants only. On an oval, marquise, pear or emerald the report gives polish and symmetry and then stops. That is not an omission on the certificate — it is how fancy shapes are graded everywhere, and it is why two ovals of identical carat, colour and clarity can look nothing alike in the hand. Three things replace the missing grade.

01

Polish & symmetry

The two finish grades the report does give. Excellent on both, or keep looking — on a fancy they are doing the work the cut grade would have done. Every fancy shape in our vault is EX/EX.

02

Length-to-width

The ratio decides whether the outline reads balanced or stretched. The trade generally looks for about 1.35–1.50 on an oval and 1.85–2.00 on a marquise. The ovals in our vault run 1.40 to 1.43.

03

The bow-tie

The dark band across the centre of an elongated stone, caused by proportions and recorded by no grade at all. It can only be seen, which is why every fancy we hold is photographed and filmed before it is listed.

04

What we do with that

We buy fancies on EX/EX finish and a length-to-width inside the preferred band, then show you the stone rather than asking you to trust a grade that does not exist for it.

05Shapes

Choosing the right cut for your client.

Round brilliant remains the benchmark for light performance — the others each solve a different design brief. Ask Lira to search any of them by carat and budget.

Round Brilliant

The benchmark for light performance. Holds value best.

Oval

Creates the illusion of greater size per carat.

Cushion

Suits vintage and halo settings beautifully.

Pear

Spreads large; elegant point demands a protective setting.

Marquise

Elongates the finger; the largest face-up per carat.

Emerald

Step-cut clarity showcase — pairs with higher clarity grades.

Radiant

Brilliant faceting in a square outline — suits channel and bezel work.

Heart

A statement cut that requires skilled setting.

06Certification

What the IGI report tells you.

Every Nuriel stone arrives with an IGI report. The report number is laser-inscribed on the girdle — verifiable under 10× magnification for the life of the stone. IGI is accepted by all major insurers and valuers in New Zealand and Australia.

Verify a report on IGI.org ↗ Anatomy diagrams →

Why IGI, and only IGI.

GIA is the name most of your clients will have heard, so this is worth two minutes. Nuriel grades every stone with IGI, and the reason is consistency rather than preference: one laboratory means one scale, so every stone in the vault is directly comparable with every other one. When reports come from two different labs you end up explaining to a client why a G from one reads differently from a G from the other — and that conversation loses the sale more often than it wins it.

IGI grades lab-grown diamonds at scale and issues full reports for them, which is why most lab-grown supply chains run on it. One thing worth knowing whoever you buy from: the major laboratories do not all describe lab-grown stones the same way, and reporting practice has changed in recent years. So when you are handed any report on a lab-grown stone, read what that particular document actually states rather than assuming it maps onto the natural-diamond scale you already know. Every Nuriel report can be checked on IGI's own site in seconds — before you commit to a client, not after.

IGI ReportWhat it covers

Report number

Unique ID, laser-inscribed on the girdle

The 4Cs

Carat · colour · clarity · cut grade

Finish

Polish · symmetry · fluorescence

Proportions

Table, depth, crown & pavilion angles

Plotting

Diagram of clarity characteristics

Growth

Identified as laboratory-grown, CVD or HPHT

07The lab-grown case

Same stone. Different story.

— What Nuriel supplies

Lab-grown diamond

Composition

Pure carbon, crystallised over 6–8 weeks via CVD or HPHT

Hardness

10 / 10 on the Mohs scale — identical

Grading

Same 4Cs scales · IGI · laser-inscribed

Origin

Conflict-free by definition

Trade price

25–40% below mined at identical grade

— For comparison

Mined diamond

Composition

Pure carbon, crystallised under the earth's mantle

Hardness

10 / 10 — same hardness

Grading

Same international grading scale, adopted by all major labs

Origin

Variable. Kimberley Process is paper, not a guarantee

Trade price

Premium driven by scarcity narrative

The Lab-Grown Diamond, Understood

How a lab-grown diamond is made.