"The stone's clarity wasn't even on the chart, it was very bad," she said.
In addition, the company's return policy only allowed 10 days to return the stone, she said.
"That's a very quick turn-around time, sooner than most businesses. Such quick return warranty policies send up red flags," said Vance.
"A good reputable jeweler usually stands behind a product," she added.
Vance said if it sounds to good to be true, it's probably not true.
"If you buy a bad stone, you can't trade it in. No one wants to buy it from you, so you can end up stuck with it," she said.
Vance said research and preparation may prevent financial and emotional heartache.
And while the Internet is a popular tool, it shouldn't be a consumer's only source of information.
"I highly recommend meeting with a jeweler face to face, someone you feel you can trust," she said.
The selection and purchase of a diamond is often more involved than the purchase of an automobile and as complicated as the purchase of a home, according to the American Gem Society Web site.
Established in 1934, the American Gem Society is dedicated to setting the highest possible standards of business ethics and professionalism in the jewelry industry, the organization's Web site said.
"Customers should even seek out jewelers who are members of the American Gem Society," said Tom Newcomer, a certified gemologist and owner of R. Bruce Carson Jewelers in Hagerstown.
"When setting out to buy a diamond, customers should look for the four C's ," he said.
The four C's represent a diamond's cut, clarity, color and carat. Each is measured separately, but when combined all four determine a diamond's value, Newcomer said.
Customers should request a diamond grading chart that measures and defines the quality of a diamond's cut, color and clarity, he added. The Gemological Institute of America, one of the world's premier diamond labs, has developed a grading chart customers may request when visiting a jeweler, said Newcomer.
"The chart helps you understand what you're getting and what you're not getting. If you enter a shop and the jeweler doesn't have a diamond microscope, you want to check his or her credentials," said Newcomer, who hangs his gemologist certification in clear view behind the counter.
Long-time customer Donna Kaye-Haines, of Hagerstown, said she believes a jeweler's reputation is one of the most important traits to look for when shopping for a fine piece of jewelry.
"But I'm finding that the person on the other side of the counter isn't always the best trained person to consult on a fine jewelry purchase," she said.
Independent appraiser and certified gemologist Gary Lester of Owings Mills, Md., said a growing number of customers are confronted by sales staff who aren't always thoroughly trained to assess the quality and value of a diamond.
Newcomer said obtaining lab reports that verify a diamond's condition is one of the best forms of consumer protection.
The American Gem Society Laboratories and the Gemological Institute of America are two leading U.S. labs that offer written reports verifying a diamond's characteristics, Newcomer said.