The ruby set is made out of rubies. Rubies can be smelted into Fine Rubies to craft the Terrorizor, but if you throw a fine ruby in your crafting table, you can get a regular ruby back, like reversing the smelting. Ruby has very high durability on armor but not on tools, a little better armor, better mine speed, and a little better damage. The ruby texture is slightly differently saturated and different colored to avoid copyright or whatever. Ruby is a tier above diamond.