Understanding Lab-Grown Diamonds: How They Are Made and How LOHR Grades Them

Understanding Lab-Grown Diamonds: How They Are Made and How LOHR Grades Them

Lab-grown diamonds are real diamonds. Chemically, optically and physically they are identical to mined diamonds — the same crystal lattice of carbon, the same hardness on the Mohs scale, the same brilliance and fire. The only difference is where they were made. Mined diamonds form over hundreds of millions of years deep within the Earth; lab-grown diamonds are produced in controlled laboratory conditions over a period of weeks using one of two well-established processes.

How lab-grown diamonds are made

Two industrial processes produce gem-quality lab-grown diamonds:

  • High Pressure High Temperature (HPHT) — replicates the natural conditions deep within the Earth. A small diamond seed is placed in a chamber with a carbon source and exposed to extreme pressure (around 1.5 million pounds per square inch) and temperatures of around 1,500 degrees Celsius. Over weeks, the carbon crystallises onto the seed.
  • Chemical Vapour Deposition (CVD) — uses a vacuum chamber filled with carbon-rich gases. A diamond seed is placed in the chamber and the gases are heated to several thousand degrees, breaking down their molecular bonds. Carbon atoms then accumulate on the seed, layer by layer, forming a diamond crystal.

The Australian Federal Trade Commission and the FTC's Jewelry Guides (16 CFR Part 23) confirm that lab-grown diamonds and mined diamonds are both diamonds. The relevant disclosure rule is that retailers must clearly identify which is which, so consumers can make an informed choice.

How LOHR sources and grades

Every lab-grown diamond used in a LOHR piece is selected against an internal grading specification covering the standard 4Cs (carat, cut, colour, clarity) plus polish and symmetry. We do not sell SI2-or-lower clarity stones in solitaire settings; for melée and side-stones, our minimum is VS clarity, F-G colour, Excellent or Very Good cut.

For all centre stones over 1 carat, we provide an independent IGI (International Gemological Institute) authenticity certificate with the piece on delivery. IGI is one of the world's largest independent gemmological laboratories and has issued certificates for both mined and lab-grown diamonds since 1975. Sub-1 carat stones, melée and pavé settings are graded internally to the same specification but do not carry an individual certificate.

What to ask before you buy

  • Is the stone lab-grown or mined? The retailer must tell you clearly.
  • What is the carat weight, colour grade, clarity grade, cut grade?
  • Is the centre stone independently certified? By which laboratory?
  • What metal is the setting — platinum, 18ct yellow gold, 18ct white gold, 18ct rose gold?
  • What is the warranty period and what does it cover?
  • What is the production timeline if it's made-to-order?
  • What is the returns/resizing policy?

References

If you have any questions about a specific piece, our materials, certification or sourcing, please get in touch or book a consultation at our Brisbane showroom.