Who says engagement rings must only be diamonds? In fact, history shows us that in centuries past, the symbol of love could be made with plants and iron. Diamonds were even rarer then, making them an option only for the wealthy – rulers and royalty.

Gemstones were a more approachable alternative for the proletariat set. And, their vibrant colors and shapes are making them an attractive option today for couples looking to customize their betrothal jewelry.

While it’s still not common to find gemstone engagement rings at chain jewelry stores, such as Zales and Robbins Brothers, higher-end jewelry dealers and Web sites are offering the look using traditional jewels such as sapphires, rubies and emeralds along with trendier varieties of tanzanite, aquamarine and green tsavorite.

At Los Angeles-based Angara.com, an online jewelry retailer, emerald engagement rings are the No. 1 colored gemstone choice in the category, according to Zameer Kassam, Angara.com’s vice president. He said emeralds may have received a popularity boost courtesy of Angelina Jolie, a Best Actress nominee who attended the 2009 Academy Awards wearing rock-sized emerald earrings provided by Lorraine Schwartz.

“Diamonds are common now - it seems like three out of every four women have the same diamond rings,” Kassam says. “We love diamonds at Angara, but we see that there are a massive number of women who don't want what everyone else has, but want something unique and special – a Colombian Emerald with diamonds or a Pigeon Red Ruby Solitaire for example – that she knows is hers and hers alone.”

During a recent sale at Angara.com, prices ranged from $699 for an oval emerald flanked by diamonds to $7,999 for a massive, three-carat emerald cocktail ring accented with diamonds.

For even more lustrous baubles, future fiancés can visit the Web site of Manchester, New Hampshire-based Bijoux Extraordinaire at www.jewelryexpert.com. The company specializes in antique jewelry and Art Deco designs and showcases a number of custom designs online, including a 4.5-carat violet-blue tanzanite ring set in platinum, made for “a Manhattan executive” and an emerald-cut pink sapphire ring set between tiers of diamonds priced at $14,750.

Indeed, the appeal of gemstone engagement rings may be the limitless options. Sapphires alone can be found in a host of colors from orange to yellow to purple. Just be sure that the ring is certified in the color stated. Also, buyers shopping for colorful engagement rings should verify that the gemstone hails from terra firma, Kassam says. Some jewelers sell lab-made gemstone rings, which may ring hollow for some brides.