Ruby, created by Japanese developer Yukihiro "Matz" Matsumoto in the 1990s, was given its name because it was influenced by Perl.
A fascinating instant message exchange between Matz and his colleague Keiju Ishitsuka shows how they deliberated over a number of alternatives related to pearls and shells including oyster, bisque and coral before they eventually settled on Keiju's first suggestion: ruby. Here is an extract:
>keiju> a jewelry name after all
>matz> put it alongside kanji?
>matz> why jewel's name?
>matz> the influence of Mitsubishi?
>matz> I see
Matsumoto would later say he chose Ruby over Coral because it was a colleague's birthstone. He also later realised that Ruby comes after Pearl in the birthstone sequence: June's in pearl, July's is ruby.
Sources: The History of Ruby | Chat thread between Matsumoto and Keiju Ishitsuka | Why the name Ruby?