These gloves can be obtained by bringing the magical family gauntlets to Johnathon, one of the sons in the Family Crest quest. Johnathon is located upstairs in the Jolly Boar Inn, which is northeast of Varrock. If you bring the gauntlets to Johnathon after you have already imbued them with another power, you must also bring 25,000 coins to change them. If dropped or lost due to death, these gauntlets may be re-obtained free of charge from Dimintheis and will have the same enchantment on them.
Chaos gauntlets were quite popular before the Evolution of Combat due to the high cost of the death runes required for Blast spells, and they allowed bolt spells to hit almost as high as blast spells. They are now largely unused due to the low cost of all standard combat spells and players generally having much higher Magic levels. The damage boost is also much smaller in comparison.
When you pay Johnathon to change your gauntlets, you will see this message: "Johnathon takes your gauntlets from you, and begins a low chant over them. You see them glow and sparkle, before he returns them to you."
After the Evolution of Combat was released, they no longer gave a damage boost to all bolt spells; they were purely cosmetic. This damage boost feature returned 24 March 2014.
The gauntlet's name comes from the fact that all bolt spells used chaos runes before the Evolution of Combat.