Is a lost diamond covered by insurance?

I'm curious to know, when it comes to valuable items like diamonds, are they typically covered by insurance in case of loss? I've heard of insurance policies that protect against theft or accidental damage, but what about a lost diamond? Does insurance typically extend to cover such a scenario? And if so, what are the specific conditions or exclusions that one should be aware of when considering such coverage? I'm eager to learn more about the ins and outs of insuring valuable gems like diamonds.