My fiancée lost her engagement ring...will homeowners cover this?

Highly unlikely but depends on how you covered your ring. If you did not list it for special coverage it will only be covered for a maximum of $1,500 (sometimes other amounts) for theft only usually. Unless you scheduled personal property for the ring for the full value. If you did schedule the property for the full value it will also cover the ring anywhere in the world even for mysterious disappearance.

Without the endorsement you'll need to contact your agent to see what the policy language states to see if it is covered and if so for what amount, but it is unlikely to be covered.

I just got engaged myself and the first thing I did before accepting the ring from the jewelry shop was to get my scheduled personal property endorsement added to ensure that if anything did happen I wouldn't lose out.

I doubt it. You normally have to have a separate rider to cover jewelry, artwork, and collectables.

well that proves how important the ring was to her!!!