By Roland Piquepaille
In "The many facets of man-made diamonds," Chemical & Engineering News (C&EN) writes that synthetic diamonds are getting bigger and cheaper. An example: for Valentine's Day, you can buy a yellow colored man-made diamond, visibly indistinguishable from a natural one, for $4,000 per carat. This is a 30% discount when compared with a natural diamond. This long article from C&EN also says that if synthetic diamond makers are targeting the jewelry market first, these new products will have an impact on many other industries.Before going further, here is a photo of a rough yellow synthetic diamond from Gemesis Corporation (Credit: Gemesis).
This press release from the American Chemical Society, who publishes C&EN, gives some essential details.
The diamond-making business has been around for years and although synthetic diamonds had many important uses, including saw blades, drill bits and exfoliants, they were tiny and not gem quality. Only recently has chemistry been able to grow large, gem quality stones at approximately one-third the price of mined diamonds, says C&EN.
Companies such as Gemesis in Florida and Apollo Diamond in Boston are now creating lab-grown diamonds that can be produced to more than a carat in size and are virtually indistinguishable from their mined counterparts, says the newsmagazine. They are chemically and physically true diamonds.
Synthetic diamond-makers start with a tiny diamond "seed" around which the new diamond grows. But that's not chemistry's only role in the diamond market. Even natural diamonds can be changed with chemistry, says the newsmagazine.
Colored diamonds, which are valuable and very rare, can be created by introducing carefully controlled elemental "impurities" into the stone, says C&EN. For instance, nitrogen produces a yellow stone. Infusing boron into the growing diamond produces a blue gem.
It is well-known that a diamond has an extraordinary range of materials properties, as C&EN reminds us.
It is the hardest and stiffest material known; is an excellent electrical insulator; has the highest thermal conductivity of any material yet barely expands when heated; is transparent to UV, visible, and infrared light; and is chemically inert to nearly all acids and bases.
But if diamonds have remarkable prperties, they are too expensive and too small to be used by many industries.
"Plus, with natural diamonds, you can't control the type or placement of dopants," notes James E. Butler, who is spearheading attempts to study, grow, and use diamond at the U.S. Naval Research Laboratory. As a consequence, Gemesis and many others are eager to create large synthetic diamonds with carefully selected impurities -- for instance, boron-doped semiconducting diamonds that could be used to fabricate diamond-based electronic devices that could stand up to heat and chemical attack.
But high-pressure, high-temperature methods of synthesizing diamond like Gemesis' offer limited control of impurities and produce diamonds of limited size, Butler says. Apollo Diamond, a start-up company in Boston, thinks that a low-pressure technique called chemical vapor deposition (CVD) could be the answer.
Apollo is using CVD to grow single-crystal diamond wafers big enough to be cut into diamond gemstones of a carat of more. Apollo's method can grow larger diamonds and is less expensive than high-pressure, high-temperature methods, notes Robert C. Linares, Apollo's founder and chairman.
This photo shows plates of very pure diamond grown by Apollo using CVD (left) that can be cut and polished into beautiful gems (right) (Credit: Apollo).
Please read the original article for many other interesting technical explanations. And if you want to choose a gem for Valentine's Day, be sure to visit this gallery. All jewels are available online -- providing that you have enough money.
Sources: Amanda Yarnell, Chemical & Engineering News, February 2, 2004; American Chemical Society press release, February 10, 2004
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