WHAT ARE LAB-GROWN DIAMONDS?
Perfect Diamonds from the lab.
Lab-grown diamonds are artificial diamonds produced exclusively in the laboratory by means of a technological procedure. Unlike natural diamonds, they are not the result of a process that occurs over thousands of years. Diamonds found in the earth are extremely rare. Today their expensiveness is determined largely based on the high amount of effort required to find and mine them.
Lab-grown diamonds are of great importance for the world of technology and electronics and are winning greater significance for the gem and jewelry industry. The continuous development in manufacturing techniques allows for the production of products of even greater size and quality. This also requires, however, routine recognition methods to categorically differentiate between natural and synthetic diamonds.
The amount of time it takes to create a synthetic diamond differs, depending primarily on the size of the preferred product. Most synthetic diamonds are man-made by means of the following two technological processes.
| Properties | Natural Diamonds | Synthetic Diamonds |
|---|---|---|
| Chemical Properties | Carbon (С) | Carbon (С) |
| Refractive Index | 2,42 | 2,42 |
| Dispersion | 0,044 | 0,044 |
| Hardness on Mohs Scale | 10 | 10 |
| Density | 3,52 | 3,52 |
| Luster | 17,20% | 17,20% |
| Trade Name | Natural | Cultured |
HPHT Process
(High Pressure, High Temperature)
For this method, a press is used to mimic the very mass, pressure, and temperature required for a diamond’s growth exactly as it occurs in the natural process.
Artificial diamonds have been produced in the laboratory since the 1950’s. The process is based on the conversion of pure graphite into cubic-type diamond in a hydraulic press at the natural formation conditions of about 50 kilobars and 1400°C.
Synthetic diamonds contain low concentrations of nitrogen and belong to type Ib, and more rarely type IaA.
CVD Process
(Chemical Vapor Deposition)
CVD is a completely different method of production by which synthetic diamonds are formed out of a hydrocarbon gas mixture. This method is preferred by laboratories as it provides significantly more flexibility and is easier to execute. This process was already investigated in 1952 by William G. Eversole—the full procedure, however, wasn’t developed until the 1990’s.
Synthetic CVD diamonds are characteristically pure and have a tabular appearance. The plates are used specially for technical applications. Due to its thinness, this equipment is used to manufacture smaller brilliants at best.
During the production of synthetic diamonds of jewelry-quality, the carbon atoms of the carbon-hydrogen mixture deposit at temperatures of 900 to 1200°C onto a germ crystal of natural or synthetic diamond and spur the growth of the crystal. Synthetic diamonds cultured via the CVD process belong to type IIa.