With insurance, the insurance company wins over the people; that's what those actuaries do and that's why you pay the premium that you do. However, people get insurance in case that particular disaster would be "catastrophic" for them financially. So, think home insurance (what would you do if your house burned down) or health insurance (if you get cancer?). This element is missing from the engagement ring purchase. If it is lost or stolen, you may be upset, but financially, are no worse off than if it hadn't been. You probably wouldn't end up relying on the engagement ring as an income source - it would have just been kept as a token.