Veronica Diamond ((EXCLUSIVE))

Abstract: The ultrasonic seeding of a substrate with diamond suspensions enriches the surface with nanometre-sized seeds that coalesce and form a closed conformal film during early stages of diamond growth. To get insight on seeds early growth and evaluate the seeding efficiency of different suspensions, silicon samples were exposed to diamond growth conditions before seeding; this leaves a thin carbon film on the substrate surface. Following this step samples were seeded with commercial nanodiamond suspensions, exposed again to growth conditions and characterised by SEM. Results showed that seeding suspensions played a role depending on particle size and nature of dispersing medium. Seeding density was larger and more uniform in samples pre-exposed to diamond growth conditions. The carbon film deposited during the pre-treatment improves deagglomeration of nanodiamond seeds via a more effective interaction between substrate surface and seeds. This procedure represents a viable way to grow thin conformal diamond coatings by HFCVD.

veronica diamond

LONDON (Reuters) - Since De Beers abandoned its decades-old policy of refusing to sell lab-grown diamonds as jewelery, the price gap between man-made stones and natural gems has widened - and the difference is set to get even bigger.

When De Beers shocked the industry with its U-turn in May, a 1 carat synthetic diamond cost about $4,200 while an equivalent mined gem sold for $6,000. But since September, De Beers, has been selling gem-quality man-made stones for just $800 a carat.

De Beers says it wants to create a clear distinction between lab-grown diamonds and natural gems. The hope is this will reinforce the mystique of stones formed in the earth's crust so consumers keep buying them for major events such as engagements.

By contrast, its synthetic diamonds grown in Britain at its Element Six labs and sold through jewelery subsidiary Lightbox are marketed as sparkly, pink, blue or white fashion accessories that are neither as rare nor precious as real gems.

But so far, De Beers' strategy has been working. According to analyst Paul Zimnisky , the average discount of a 1 carat generic lab-grown diamond to a natural diamond had widened to 42 percent by mid-November from 29 percent in January.

At the same time, production costs to make high-tech diamonds in a laboratory have plummeted to as little as $300 a carat from about $4,000 over the past decade, according to consultants Bain & Company and two former De Beers' employees.

That means De Beers has plenty of scope to cut prices further, to reinforce the cachet of natural gems and to undermine synthetic diamond rivals that have been earning substantial margins in recent years, analysts say.

"The cost of these synthetic diamonds will go down to production costs plus a competitive profit margin. There is no shortage," said Martin Rapaport, who publishes a list of natural diamond prices regarded by many in the industry as a benchmark.'SUBSTITUTION SCENARIO'

De Beers is also investing $94 million over four years to build a U.S. factory that will churn out 500,000 carats of lab-grown gems a year and Chinese producers are stepping up their output of cheap manufactured diamonds.

"I think De Beers will keep the pressure up and may even cut prices further from the $800 level once they get their new factory up and running," a diamond industry executive who used to work for De Beers said on condition of anonymity.

The industry has attracted investors from Silicon Valley and Hollywood, including "Blood Diamond" star Leonardo DiCaprio, who helps promote man-made diamonds as ethical and low-carbon - claims that are disputed by the natural diamond sector.

"The idea of De Beers is clearly to set a price point where it may deter large volumes of capital to come into the lab-grown diamond market," said Morgan Stanley analyst Menno Sanderse. "They are trying to minimize the tail risk of the substitution scenario."

California's Diamond Foundry , backed by DiCaprio and Silicon Valley investors, is among dozens of lab-grown gem producers to emerge over the last decade as technology has evolved since the first synthetic industrial-quality diamond was created in 1954.

While the natural diamond industry includes miners, traders, polishers, jewelery makers and retailers, all adding their own margins, the man-made sector controls many if not all of those functions in single firms.

Major department stores J.C. Penney and Macy's announced in October the roll-out of a bridal collection of lab-grown diamond jewelery in time for the peak Christmas season - and stuck to their guns on pricing. 041b061a72