If the entire house burns down, all your items are covered subject to the terms of the policy like contents limits. However, for Theft Only you should purchase additional coverage if you have lots of jewelry, expensive watches or even furs. You can extend or endorse your coverage to up to $5,000.00 for the theft of these items stolen from your home.
If you have one piece of jewelry you are particularly concerned about, you might want to look into a Jewelry Floater. A Jewelry Floater covers one specific piece of jewelry, for example, a wedding ring. The advantage of a floater is the coverage is All Risk of physical loss. So if you lose a stone, break a clasp or drop it down the sink, the policy will cover that item for the amount it is insured for.