In the original PlayStation 2 versions, the ring can be bought for 16,000 gil from Old Archades (before obtaining Treaty-Blade) and from Balfonheim Port. It is found in a treasure in Ridorana Cataract's Echoes from Time's Garden (in the middle of the the east edge; 50% chance to appear, 50% chance for gil, 50% chance the item treasure is Opal Ring without the Diamond Armlet ).
In the updated Zodiac versions, Opal Ring can't be bought from shops, but sells for 6750 gil. It is found as a treasure in Pharos - Second Ascent's Station of Banishment (always appears), in Subterra's Abyssal - North (70% chance to appear, 80% chance for gil, 50% chance the item treasure is Opal Ring without the Diamond Armlet) and in Nabreus Deadlands' Lifeless Strand (25% chance to appear, but is always the Opal Ring), as well as in the Trial Mode stages 79 and 92 with the Diamond Armlet equipped.
It can still rarely be stolen from the Grenade and made in the bazaar in the "Exquisite Ring" set with the same requirements as before.
The Opal Ring allows the wearer's spells to pierce the target's Reflect status. It is useful for healers when the party has Reflect, such as during strategies to bounce area spells off multiple party members to "multi-cast" them onto enemies, or against enemies that protect themselves with Reflect, like the Dead Bones that spawn around where Roblon is fought on the Nabreus Deadlands, or the Mirrorknights in Feywood.
Opal is a hydrated amorphous form of silica classed as a mineraloid, unlike the other crystalline forms of silica, which are classed as minerals. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock. The internal structure of precious opal makes it diffract light; depending on the conditions in which it formed, it can take on many colors. Precious opal ranges from clear through white, gray, red, orange, yellow, green, blue, magenta, rose, pink, slate, olive, brown, and black. Of these hues, the reds against black are the most rare, whereas white and greens are the most common. It varies in optical density from opaque to semitransparent. Common opal, called "potch" by miners, does not show the display of color exhibited in precious opal.