Are synthetically-produced diamonds as hard as natural diamonds? I was having a discussion with my friend about the intrinsic worthlessness of diamonds (DeBeers and whatnot) and how synthetic diamonds haven't caught on, again because of the marketing/propoganda that natural diamonds are "better". My friend, partially to spite me because he doesn't like to lose an argument, claims that synthetic diamonds have only been produced with a hardness up to 9.8, and you can only get a hardness of 10 with a natural diamond.
I call BS on that. A little research indicates that while natural diamonds may slightly vary in hardness (the impurities which alter the color also modify its crystal properties), synthetic diamonds have a more consistent hardness which is otherwise identical to a naturally-occurring diamond with the same chemical properties. This appears to make sense.
Are chemically-identical synthetic and natural diamonds of equivalent hardness? Or is there a caveat to the synthetic diamond-making process that produces weaker diamonds?
 A: The laboratory made diamonds are as good as the naturally found ones. It is the same crystal structure. They are not used much as gemstones, (2%  of the market) because of the objections of the diamond industry which relies on mined diamonds and dominates the markets.

Gem-quality diamonds grown in a lab can be chemically, physically and optically identical (and sometimes superior) to naturally occurring ones. The mined diamond industry has undertaken legal, marketing and distribution countermeasures to protect its market from the emerging presence of synthetic diamonds. Man-made diamonds can be distinguished by spectroscopy in the infrared, ultraviolet, or X-ray wavelengths. The DiamondView tester from De Beers uses UV fluorescence to detect trace impurities of nitrogen, nickel or other metals in HPHT or CVD diamonds.[

A: Natural diamonds are slightly harder than synthetic diamonds. This is very commonly known in manufacturing (diamond-tipped drills etc) and there is plenty of engineering resources on the subject. However for jewelry purposes, a trained jeweler can almost never pick out a real vs synthetic without special tools for that purpose.
