  Gem cut aluminum oxide (corundum). 
These are real rubies and sapphires purchased from http://www.pehnec.com in April 2002.  Real because they are chemically and crystallographically indistinguishable from naturally occurring gems (that would cost well into 5 figures).  Present in the table because they are man-made (real, but synthetic).   
Source: Pehnec Gems 
Contributor: Theodore Gray 
Acquired: 23 April, 2002 
Price: $15/both 
Size: 0.6" 
Purity: 53%
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