DENVER -- Just about everyone has heard the advertising slogan "a diamond is forever" and we've heard diamonds are said to be among the hardest substances on earth. But some diamonds used in jewelry may stay intact for just a few years and some lifetime warranties may be worth less than the paper they're printed on.

Lori Connor purchased a diamond ring at Tiffany & Co. four years ago. A chip developed in the ring last year and she took it back to Tiffany. Connor said Tiffany remounted the diamond to protect it. The store said Lori refused to have the diamond repolished to remove the chip.

Two months ago, another more substantial chip developed -- an "L" shaped crack that runs from the upper right to the bottom of the diamond. Connor took the ring in again.

"I expected that since there was extraordinary damage and since I'd gotten the ring at Tiffany, I would get an extraordinary response," said Connor. "They said there was nothing they could do, that it was extraordinary damage to the diamond, that they'd never seen anything like that from one of their diamonds."

Certified gemologist and appraiser Neil Beaty inspected the ring at Call 7's request.

"This is worse damage than you usually see, but yes, it is common for diamonds to chip," said Beaty.

He quickly shattered the myth that diamonds are unbreakable.

"It happens with some frequency. They are hard. They are brittle. They're difficult to scratch, but you can crack them," he said.

Beaty said the warranty is up to the retailer, "But that's not about the diamond. That's about the store."

Tiffany said the first time Connor brought in the ring the mounting was worn, dented and heavily scratched, and it suggested her lifestyle might be the cause. But Connor works in a spa in Aspen.

Beaty said the damage could have come from just tapping the ring the wrong way on a hard surface and doing it often.

Tiffany promises that its diamonds are of the highest quality with a lifetime warranty that the diamond you bought meets specific diamond characteristics. But the warranty specifically excludes any damage to the diamond that happens after the sale.

"They said the lifetime warranty said that what they sold me was what they sold me," said Connor.

7NEWS checked warranty policies at 11 other metro area jewelry stores from big chains to locally owned single stores. Seven said their warranties covered chipping or breaking, with requirements to bring the ring in regularly for cleaning and inspection. The other four did not cover damage to diamonds.

If you have problems with a diamond and the jeweler doesn't respond you may be protected on your homeowners' insurance policy. Ask your agent about your coverage before you need to file a claim.