Ruby equipment (ルビー, Rubī?) is a recurring set of equipment in the series. They are generally far fewer in numbers than most other recurring equipment sets, and are most commonly found in the form of armor and accessories.
Ruby equipment tends to fall into the lower power category of equipment, as it is generally weaker than Mythril equipment and Gold equipment, but stronger than Leather equipment, Bronze equipment, and Silver equipment. The most commonly recurring Ruby equipment is the Ruby Ring.
The first appearance of the Ruby equipment comes in the form of the Ruby Armlet, which is the mid-ranked armlet, being stronger than the Silver Armlet and Copper Armlet, but weaker than the Diamond Armlet and Thief's Armlet. It provides +24 Defense and +1 Weight, and can be bought for 50,000 gil at Gaia or found in the Citadel of Trials.
The Ruby Cuirass is the mid-ranked Cuirass, being stronger than the Copper and Silver Cuirasses, but weaker than the Gold and Diamond Cuirasses. It provides +15 Defense, -5% Evade, +5% Magic Defense, and -1 Intelligence/Spirit. It can be bought for 800 gil (600 in non-NES and PS versions) at the Tropical Island, or found at Paul's House.
The Ruby Ring is the second-weakest armlet, and is again the only piece of Ruby equipment.
Ruby Ring returns in the sequel of Final Fantasy IV and its the sole piece of Ruby equipment while being the weakest armlet. It is initially equipped on Rydia, and can be equipped by all characters. It can be bought in Damcyan Castle and Fabul Castle for 1,000 gil. It can also be found in the Developer's Office inside the Tower of Babil. It has a defense of 0, magic defense of 3, magic evasion of 2, and grants protection from Pig.
The Ruby Ring again is the sole Ruby equipment, and retains all of its stats and abilities as before.
Several pieces of Ruby equipment exists, being the Ruby Shield, Ruby Ring, Ruby Bracer, Ruby Armguard, Ruby Armlet, Ruby Bangle, and Ruby Targe. All Ruby equipment are obtained if the dominant abilities on any armor are any four Magic Defense +% abilities.
The sole piece of Ruby equipment is the Berserker's Ruby, which provides Enhanced Commando and has 35 Capacity.
The Ruby Earring returns as the sole piece of Ruby equipment in this installment, only now providing immunity to Charm.
The Ruby Studs is the sole Ruby equipment, which provides +5 Attack, Defense, and Magic.
The Ruby Studs is the sole Ruby equipment, which grants +5 Fire to both Elemental Attack and Defense.
The Ruby Hourglass and Ruby Armor are the only Ruby equipment. Ruby Hourglass provides EX Mode Duration +10% and EX Mode Damage -10%, while the Ruby Armor is a level 60 heavy armor that provides +2897 HP, +34 Bravery, and Physical Defense +5%.