Today I also watched Eureka and was intrigued by the possibilities that a "Logic Diamond" does or could exist.
Based on my research, the following link on the geek.com website contains an article written by J. Eric Smith; posted on August 27, 2003.
The article addresses:
*High temperature characteristics of diamonds,
*The development of inexpensive diamond semiconductor wafers, and
*An experimental diamond transistor clocked at 81Ghz. Compare that to current day CPU frequencies.
This appears to come close to the concept of the "Logic Diamond".
Remember this article was written in 2003. I am sure other advances have been made since then.
After you read the link above, then view:
General information on the characteristics of diamonds can be found at: http://en.wikipedia.org/wiki/Material_properties_of_diamond
If I find more, I will post it later.
Thanks for asking!