You've practically gotta be a Rockefeller to buy an adequate rock for your honey these days.

The average price for an engagement diamond has soared to a record $2,600.

And the trend is heading toward even bigger — much bigger — stones, thanks to cash-laden baby boomers egged on by gem-heavy, newly engaged stars like Katie Holmes (search) and Paris Hilton (search).

"You just have a massive amount of cash out there," said Peggy Jo Donahue, editor of Professional Jeweler magazine, which reports on the industry for U.S. retailers.

More disposable income means bigger, more extravagant luxury items, she said, and that includes larger, rarer, pricier stones.

"It's a perfect storm of baby boomers beginning to inherit money, beginning to retire, with many still in their peak earning years," she said.

"When you have a lot of wealthy people trying to best each other, you're going to have larger and larger [stones]."

Helping to boost the overall market are one-carat diamonds, with sales jumping a whopping 80 percent since 1996, according to The Wall Street Journal.

Donahue said that increase was basically tied to the dot-com boom, which dropped tons of cash into the economy.

Even after the 2001 terror attacks, as the general economy took a hit, the diamond market continued to flourish, experts said.

At giant online jeweler Blue Nile, first-quarter sales reportedly jumped 23.3 percent this year.

Publicity-hungry stars who flaunt their priceless baubles before the cameras are prompting a feeding frenzy for larger stones.

Donahue said Jennifer Lopez's (search) 6.1-carat pink engagement diamond from Ben Affleck sparked a rush for colored stones.

And when the female stars of "Sex and the City" touted right-hand rings in publicity photos, more women sought out similar jewelry, she said.