The upcoming holiday season is the most popular time of the year to pop the question. So if you're proposing marriage, it's best to be prepared.

And, if you're a nervous groom intent on surprising your bride-to-be, remember that round diamonds still rule in engagement rings.

"You never go wrong with a round. Round is the most highly demanded shape," said Michael Kurtz, one of the owners of Goldstock Jewelers in Downtown's Clark Building.

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But for couples who long for something different and distinctive, colored gemstones such as rubies or sapphires -- which come in many shades other than blue -- are replacing the diamond solitaire as the centerpiece of an engagement ring.

"Five or 10 percent of brides have chosen something other than a diamond," said Robert Levine of Robert T. Levine Designs in Downtown's Arrott Building.

This is true for young couples who shop together for an engagement ring and wedding bands, as well as mid-career professionals marrying for the second time.

Couples may also decide to have their rings custom-made. And while that process may take up to two months, it's easily done in Pittsburgh. Besides Robert T. Levine Designs, there's Keith Belles, who opened Wax Jewelry Design Studio in Shadyside.

Since moving to Pittsburgh in 1984, Mr. Belles has worked for several jewelers in the Clark Building, including Don Conkey.

For 12 years, he served as principal designer, wax carver and shop manager at Robert T. Levine Designs.

"Bob Levine introduced me to design," Mr. Belles said, adding that he left Mr. Levine's firm in 2000. In 2006, with his wife, Sandra Lawton, he opened Wax Jewelry Design Studio at 5901 Ellsworth Ave. Mr. Belles, who trained as a metalsmith and sculptor, loves designing jewelry with texture.

"I approach jewelry as small sculpture, not as bling," he said.

Some brides and grooms, including people in their 20s and 30s, are not interested in buying jewelry right out of a case at the mall, Mr. Belles said. One bride chose an orange sapphire engagement ring set in yellow gold. Another showed him the lace in her wedding gown and asked him to incorporate that pattern into her wedding band.

Often couples ask him, "What could you incorporate in our bands that says something about us?" One couple spent six months looking through one of his books, "The Dictionary of Symbols," before settling on a design.

The process of designing an engagement ring and bands sometimes helps couples learn more about each other. The ring "becomes an heirloom. It becomes a story that you tell your children," Mr. Belles said, adding that he is comfortable carving rings in many styles, including Victorian, Art Nouveau and ancient Egyptian designs used 3,000 years ago.

For people searching for unusual pieces, Mr. Belles also carries the work of six jewelers -- Todd Reed, Hilde Leiss, Michael Banzhaf, Matthew Naftzger, Michael Anderson and Nancy Linkin. And for men concerned about scratching their wedding bands, he's made bands out of stainless steel and titanium.

Goldstock sells engagement rings and wedding bands in 14- or 18-karat gold and platinum.

"Platinum is the most expensive because the price per ounce is higher. You have to use a lot more. It's 90 to 95 percent pure. Fourteen-karat is only 58 1/2 percent gold because they mix in the alloys of silver and copper," Mr. Kurtz said.

Some brides choose to combine their engagement and wedding bands into one single ring. One popular option is to set a diamond in the center of a band and place additional stones on either side, such as sapphires or rubies. If that appeals to you, be sure to ask if the gems are natural or heat-treated.

"Heat treatment intensifies one color in a sapphire, blue over green, for example," Mr. Levine said.

His firm designs entire lines of jewelry for designer companies in New York City and Los Angeles whose names you would recognize but he cannot reveal. Besides himself, he has a staff of two designers and five craftsmen. He rarely advertises, and his clients, whom he sees by appointment only, are referred by satisfied customers. His staff often designs jewelry for couples who marry again in mid-life and commitment rings for same-sex couples.

"If somebody is 35 to 55, they are probably not getting married for the first time. It's usually not anything like the engagement ring when they are 18 to 23. Often, these couples want a combination engagement ring and wedding band," he said.

When couples ask Mr. Levine to design their rings, he usually asks them their profession, hobbies and whether they are hard on the jewelry they already wear. Throughout the process of designing a ring, Mr. Levine said, "We're willing to change directions at any point."