It is said that the Diamond Gates are composed of glittering crystalline facets. It is also said that over the course of the Eternal Conflict, the forces of Hell fought their way to the gates on more than one occasion (at the least, five times). However, for much of its history, the gates were never breached, and as such, no demon ever gained entry into the Silver City. The greatest and most elite warriors of the Heavenly Host maintained a tireless vigil at the gates, ready to repel any who might besiege them.
The Diamond Gates were finally breached by Diablo, now a singular Prime Evil. After besting Imperius outside the gates, he let out a roar that sent the gates crumbling into rubble. Thus, for the first time, the forces of Hell gained access to the Silver City, though were repelled with the aid of a group of mortal heroes.