Basic Trope: An object that brings death, whether immediately or with time, to all those that are associated with it.
Straight: All those who handle the powerful gem end up dead.
Exaggerated: All those who know the powerful gem exists or come within a mile of it end up dead.
The gem's owners don't all die, or do so in ways that are pretty easily chalked up as bad luck rather than the supernatural. In the end most think it's just a bad reputation and not a curse, and that the gem's value and selfsame rep attract "perfectly ordinary" murderous thieves.
Or, anyone who doesn't handle the powerful gem ends up dead.
Subverted: Several people who handle the powerful gem end up dead, but it's a coincidence, nothing more.
Double Subverted: Several of those who handle the powerful gem end up dead, except it's just a coincidence because a lot of people handle it and survive just fine... until they suddenly die.
All those who handle the powerful gem end up dead... so it's kept for safe-keeping with someone who's already undead, and can't die.
All those who handle the powerful gem die instantly and yet people still keep picking the damn thing up, even when it's surrounded by dead bodies...and they're the fifth in line to touch it.
Zig Zagged: All those who handle the powerful gem have their best friend die. Except they all get revived! ... as zombies in the zombie army planned by the ancient civilization that made the gem.
The gem is just a gem.
The gem is magical, but harmless.
Enforced: "We need to make this object seem more threatening than just 'it's worth lots of money' or 'it could be bad in the wrong hands'. Let's have it kill people!"
Lampshaded: "What kind of psycho makes a gem that kills everyone who touches it?"
A character curses the powerful gem so all who handle it will die.'
Alternatively, a character will trick another character to touch the artifact for that character to die.
Exploited: An assassin pays a jeweler to embed the gem in a stolen piece of the targets jewelry in order to kill them without arousing suspicion.
A character keeps highly-trained medical staff around as he prepares to handle the artifact.
A character touches the gem and doesn't die, because he's the only one who can master the gem's power.
Anyone who knows what the damn thing is has the basic self-preservation skills to leave it the hell alone.
Discussed: "...With all these artifacts killing people around here, you'd expect the ancients spent all their time just cursing random objects."
Conversed: "Haven't the characters caught on after all that death? The gem is obviously cursed to kill people!"
The powerful gem is in the hands of vengeful people determined to pass it on to the targets of their revenge to kill them, before they themselves succumb to its curse. There are several gems, and now it is a significant threat to the world's sense of security.
There is exactly one guy who could touch it, because it was designed as a defense mechanism for him. He's dead now.
Reconstructed: The cursed gems are taken by the government and investigated for its lethal properties. This brings the war escalation from technological to magical. Gems, even harmless one, are avoided by everyone.