Small and bluish-grey, vyord crystals are found in veins deep beneath the earth that run along the remains of ancient, inactive ley lines. They are exceedingly rare. On average, a good quality vyord can fetch 25,000 gold. They are as hard as rubies and have transparent hues and smooth textures.
The ability that sets vyord crystals apart from other gems is their antimagical, slightly electrical nature. A spellcaster in physical contact with a vyord crystal will find it very difficult to cast spells. He must overcome the crystal's nullification field to cast any spell. This means a spell resistance roll, even if the spell wouldn't normally allow one. (If the target of the spell also has SR, treat the gem's SR as an unnamed bonus to the creature's SR and roll once to overcome both.) The degree of difficulty varies from vyord to vyord, with the average being a SR of 10, though values from 1 to 35 have been recorded. The degree of difficulty is directly proportionate to the value of the gem, with roughly 2,500 gold for each point of SR.
This nullification field only affects a caster in close contact with the vyord, touching his body or clothing (enough to allow a touch attack to succeed). However, due to the slightly electrical properties of the vyord, this field can can extend through electrical conductors, such as regular metal and living creatures. So, if a wizard touches a cleric, and the cleric touches a metal rod with a vyord mounted on it, both will become affected by the nullification field.
A second variety of vyord crystals exist, pink and translucent. The nullification field created by these crystals are more intense that a normal one's. In fact, it's SR is double what you would expect from a gem of its price. However, a creature who directly touches the vyord (not through metal or another electrical conductor) also gain an unnamed spell resistance bonus equal to one quarter of the gem's SR (if the creature has no SR, treat it as if it had SR 0). So, a spellcaster in contact with an average pink vyord would have to overcome SR 20 to cast spells, but would also have SR 5 against spells cast at him. Expect to pay 1,250 gold per point of gem SR, 5,000 gold per point of granted SR.
Vyord crystals are sometimes used in jewelry. Some sages speculate that that the absence of magic around a creature caused by a vyord crystal may be hazardous to one's health if kept up for a long period of time. No true evidence for or against this has been proven.
There are records of certain enterprising wizards weaving metal into the outskirts of their towers, attaching a vyord crystal to the mass of metal in a hidden location. The metal doesn't weave into the inner sanctum where the wizard actually lives, thus ensuring that invading spellcasters will have a hard time repelling his spells. Unless they levitate, fly, or cast defensive spells ahead of time, anyway.