Lab created diamonds are, obviously, diamonds made in a lab. However many people are caught off guard by the name, as you wouldn’t think that a gem produced in a laboratory would be anything like the real thing. People are often surprised to learn that lab diamonds, grown in a machine for 2-3 days, are chemically identical to real, mined diamonds that have been underground for 30 million years!
The reason that these synthetic diamonds can be so similar to the real thing is that they are produced in identical conditions, from the same materials. Basically, a spray of carbon is injected into a chamber at very high pressure and temperature, which mimics the conditions found deep in the earth. Tiny seed diamonds are used as a base, and larger diamonds crystallize out of the carbon and other trace elements which are present.
Because of some of the trace elements found naturally in the atmosphere, which are hard to completely eliminate, Lab diamonds are very often yellowish. They are often sold in this form, as ‘champagne’ diamonds are quite desirable. Also if they are set into a yellow gold ring this color cast can be less noticeable.
If clear diamonds are required however, these initial synthetic diamonds can be subjected to a second process, called HPHT. The HPHT process can be used to change the color of diamonds (controversially, it can also be used on natural diamonds to ‘improve’ the color).
Because of the costs of the equipment, lab diamonds are still a significant proportion of the price of natural stones. If shopping for a synthetic, you can tell what you are getting from the price of the stone – if it is in the tens or even hundreds of dollars, you will likely be getting a stimulant such as moissanite or cubic zirconia – fine if that’s what you are shopping for of course but not chemically identical to a real diamond.