It's a good idea to purchase insurance before picking up your engagement ring. If you're planning to add it to your homeowners insurance, questions to ask include:
What's the cost of the insurance per year, per $100 value?
Is an appraisal required or will the sales receipt be acceptable?
Do they need a photograph?
Is the ring covered during travel?
Does the policy cover loss, theft and damage?
Does the coverage include full replacement value, or is there a "like" clause? Check their definition of "like." It can mean that the diamond they give you as a replacement can be a clarity or color grade lower.
You can also obtain an insurance policy specifically for your jewelry available through jewelry stores and independent insurance agents.