R is for Ruby.

Rubies range from bright pink to deep red and are one of the most striking gemstones because of it. The name ruby comes from the Latin ruber meaning red. Rubies are part of the traditional cardinal gems, along with amethyst, sapphire, emerald, and diamond.

The Gemstone Alphabet combines a minimalist aesthetic of bold striped initial letters with geometrically striking and unusual gemstones and minerals. Science..but sexy!