When you buy a diamond ring (or any piece of jewelry) from a major retailer, they will almost always ask you if you'd like to purchase an extended warranty plan. Usually these plans cover any necessary repairs or sizing with your jewelry, as long as you follow the terms of the warranty, which usually requires that you bring the jewelry in for inspection every few months.

Jewelers tout the benefits to the plan: free jewelry inspections and cleanings! Guaranteed repairs! Free sizing! All this free for two years when you purchase the extended service plan!

Here's some important advice: Don't ever buy anything from a jeweler that doesn't inspect and clean any jewelry for free. This takes very little time and almost no one charges for these services, even if you didn't buy the jewelry from them. Almost all jewelers will also size any rings for free when you buy them. This is not a perk you get when you spend extra money; this is a standard courtesy. And lastly, any ring that needs repairs within two years (the time most of these service agreements last before you have to pay more to renew them) is a piece of junk. Granted, accidents happen and if you slam your ring finger in the car door, you probably will need to repair the ring, but most repairs are not terribly expensive -- it's rare that you ever save money with an extended warranty. If you need more costly repairs like gemstone replacement, that's where adding your jewelry to you homeowner's or renter's insurance pays off.