Wondering whether your girlfriend will say yes to your proposal is stressful enough. You’re also expected to plan the perfect situation to ask her to marry you.

But before you get ready to pop the question, you’ll need to buy the perfect vintage ring that suits her retro fashion sensibilities. To make sure that you get the best deal on your vintage engagement and wedding jewelry, use the following tips to buy her a special bauble that she will wear and love forever whether you build your own ring or go with your favorite jeweler.

1.   Know the 4C’s: cut, clarity, color and carat weight

Don’t confuse the cut of the gemstone with the shape. The cut determines the sparkle and brilliance of the diamond. The clarity ranks the internal inclusions or imperfections in the diamond. The color is a letter-grade scale that rates the absence of hue in the stone. Carat weight refers to how much the diamond weighs. The bigger the carat, the higher the cost of the stone.

2.   Consider the shape and setting of the diamond or gemstone

Popular gemstone shapes are box radiant, round, marquise, emerald cut, pear, princess, standard radiant and oval. Round-shaped stones are typically the most popular setting, but it is best to pick a shape that your fiancée loves. Top metal settings include: yellow gold (10K, 14k and 18K), platinum (the most expensive and hypoallergenic metal) and white gold.

3.    Know the proper ring size

The next time she wears a ring on her ring finger, grab it once she takes it off. Using a pencil and a piece of paper, run the pencil around the inside of the ring and take it to a jeweler who specializes in estate or vintage jewelry. He or she can use your crude drawing to help select her actual ring size.

4.    Dig like a dealer

Assuming you’ve already hit your mother or grandmother’s jewelry boxes, the best place to find vintage rings and stones are flea markets, estate sales, antique shops and garage sales. As an added bonus, a vintage ring will cost you far less money that buying a new setting and stone.

5.    Search online for vintage wedding jewelry

In the past few years, online jewelry stores account for one in every 20 purchases of retail jewelry. Prices at online jewelry stores are often much lower than those in traditional offline stores. As with any retailer, who specializes in vintage and antique pieces, be sure to check their return policies and any guarantees of authenticity before you buy.

6.    If all else fails, use a vintage stone for the ring

Perhaps you or your potential fiancée have inherited your grandmother’s wedding jewelry or another piece of heirloom jewelry. You can take this heirloom ring to your jeweler and have the stone re-set into your wedding band. Using an heirloom ring counts as “something old” in the wedding tradition and adds a sentimental touch to your bride-to-be’s engagement ring.

7.    Always get your rings insured and appraised

Once you’ve found the perfect vintage engagement ring, add it to your homeowner’s policy. Also, ask about additional riders to your policy so you can be reimbursed in case of theft or loss away from your home.