What's the Deal with Lab Diamonds?

What's the Deal with Lab Diamonds?

You may have heard about laboratory grown diamonds in the news or advertised online recently. But what are they? How do they compare to natural mined diamonds? And should you be considering buying one?

Put simply, a diamond grown in a laboratory is technically identical to one mined from the ground. They are the same chemical composition (over 99% pure carbon), structure (tetrahedral crystals), and hardness (10 on the Mohs scale), and even display the same variety in color and clarity. Because they cannot be distinguished from mined diamonds in any other way without expensive testing equipment, laboratory grown diamonds over a certain weight are always laser inscribed on the girdle (the edge) with "LG" and an identification number.

 lab diamond inscription

Beware stones marketed as 'created diamonds' or other related terminology if they are being sold for extremely low prices. Legitimate laboratory grown diamonds, while less expensive than mined diamonds, still tend to be priced at about 50-70% of the price of the latter. Still, this means if you don't mind having a laboratory diamond, you can save as much as 50% by choosing one.

The key to ensuring you are buying a diamond and not a coated cubic zirconia or other substitute is to choose a trusted dealer. Going to the same jeweler you would purchase a mined diamond from is a good start. They should be able to show you the certificate alongside the laboratory grown diamond. Labs that grade these stones include IGI and GCAL and, more recently, GIA.

The certificate will have basically the same information you would find on a grading report for a mined diamond, except that it will also identify the diamond as laboratory grown and often indicate whether it was grown using the CVD or HPHT method. It may also say "as-grown" meaning there were no further treatments to the diamond after its creation in the lab. It will include measurements as well as the clarity and color grades and the carat weight. Unlike laboratory created sapphires, which tend to be more ideal than most mined stones, laboratory grown diamonds have similar ranges of color and clarity to their mined counterparts. They are cut in all of the common diamond cuts, including princess, emerald, pear, and so on. Currently, stones in the whiter and clearer grades are similarly rare as they are in mined diamonds, but they do exist. Shop for your laboratory diamond with the same criteria in mind that you would have for a mined diamond.

Laboratory diamonds are also being created in fancy colors, such as yellow, blue, and pink. These may be harder to find, so you will have a smaller range of options to choose from than if you were shopping for a natural fancy diamond.

fancy diamond cuts

fancy diamond colors

The main difference between a lab diamond and mined one, aside from price, is the conditions under which each was formed. Natural diamonds were created millions of years ago under immense heat and pressure deep underground, which cannot be duplicated on our planet currently.

Lab diamonds start with a tiny piece of natural diamond, called a seed crystal. They undergo one of two processes: either the older method of HPHT, which stands for high pressure high temperature; or the newer CVD, which stands for chemical vapor deposition. In HPHT, the seed crystal is placed in a flux solution inside a press that exerts pressure and heat to force carbon to build up on the seed crystal in much the same way that a natural diamond would have been formed deep in the earth's crust. In CVD, the seed is instead placed in a chamber with a plasma cloud of carbon-rich gas and microwaves are used to cause the carbon to precipitate out in layers on the seed crystals, of which there can be multiples in the chamber. After either method is complete, in a matter of hours, days, or weeks depending on the desired carat weight, the rough crystals are then able to be cut and faceted much like mined diamonds. The difference is only apparent at a molecular level.

Esquema prensa bars 

(above) HPHT diamond press layout

Chemical vapour deposition machine in the LCN 
(above) CVD machine

If you find a piece you like but would prefer a lab diamond, let us know and we will be happy to send you a quote.

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