Have a beach weekend coming up? Don’t forget your diamonds.

While most people grab an old towel and a bottle of drugstore sunscreen when they head to the shore, the rich and fabulous are bringing their high-living habits poolside.

In the recent NBC "reality" show featuring Victoria "Posh Spice" Beckham, the haughty former pop star lounged outside with friends in a trendy black one-piece, the requisite oversized black sunglasses and matching sky-high T-strap heels.

And days before her recent DUI arrest, Hollywood wild child Lindsay Lohan was photographed running around in both pink and blue bikinis complemented by strappy gold high heels (to better show off her now infamous alcohol-monitoring ankle bracelet).

But looking extra swanky in a swimsuit requires a lot more than a good pair of stilettos. Perhaps Lindsay and Posh didn’t get the memo about Moszkito's $20,000 diamond-encrusted flip-flops, or Susan Rosen's $30 million diamond bikini, featuring 150 carats worth of D flawless diamonds.

Photo Essay: Getting Fancy at the Beach

Worn by supermodel Molly Sims in the centerfold of last year's Sports Illustrated Swimsuit Issue, the diamond bikini lives up to its reputation, as it's made of nothing but the world’s finest and rarest stones.

“I think it is going to be in the 'Guinness Book of World Records,'” said Rosen. “Stones like that are very hard to keep off the market. I didn’t want it to look like someone else’s work, and it was also important to me that the price point was higher than any existing work."

While a Mossimo Black for Target bikini goes for only about $18, the hottest swimwear is just a tad more expensive. Melissa Odabash is a favorite designer among seaside celebs like Cindy Crawford ... and one of her hot little '60s-inspired two-pieces, such as the Anne, will cost you $152.

“I have a huge celebrity following, but I also have the housewives, single girls and fashionista mommies that love the collection,” said Odabash.

But be warned: a complete Odabash look can run into the thousands. Tunics go for up to $800, and both Britney Spears and Beyonce have splurged on Odabash's $125 straw cowboy hat.

“European women love wearing a complete look — suit, caftan, beach bag — because they usually go from day to night. I wanted to bring that option and style to fashionable hot spots like Miami, L.A. and the Hamptons," Odabash said.

Another sexy look popular this summer with celebs like Paris Hilton, Jessica Alba and Eva Longoria is the monokini — a one-piece suit with slits or cutouts (the backless JG4B Strawberry Sunrise Swimsuit is $265.)

The buck on luxury, however, doesn’t stop at a hot outfit. Hermes has a $465 terrycloth beach towel and Bulgari boasts a pair of $430 plastic sunglasses.

But when it comes to sunscreen, the chic turn to Sisley cosmetics. Sold exclusively at Saks Fifth Avenue, Neiman Marcus, Bergdorf Goodman and Canyon Ranch, Sisley’s Sunleya sun protection, $202, works as both a sunblock and an anti-aging agent.

Coupled with Sisley's Sisleya Global Anti-Age Hand Care SPF 10, $134, the two products are meant to provide a “second skin” to fight against all effects of the sun.

“The Sunleya is the newest and latest technology. It fights free radicals, so it protects the DNA of your skin. It doesn’t allow any harmful penetration because it has reflecting microspheres,” said a Sisley spokeswoman.

As for the steep prices, Sisley customers don’t seem to mind.

“When we first came out with a $120 sunscreen way back when, people thought we were crazy, but most of our clients own everything in the entire line. We aren’t inexpensive. We are in very limited distribution and we plan to keep it that way.”

Cosmetics giant Bobbi Brown also has a high-end beach line, aptly titled "Beach." Inspired by the scent of Coppertone sunblock, the low-budget summer staple, Bobbi Brown’s beach spritz, $55, is designed to “take you back to your junior high days.”

Which begs the question: Why not just buy a bottle of Coppertone for less than $10?

Rebecca Aron, 25, thinks spending so much on a day at the beach is ridiculous.

"I think it's so stupid to spend $20,000 on flip-flops," said Aron, of Lawrence, N.Y. "You have to be pretty insecure to feel like you need diamonds on your toes to go to the beach. Is there a difference between the cotton used in an Hermes towel or is it the same terrycloth you can get at Wal-Mart for $5?"

And even if you spend a fortune on a bikini, you'll still have the same problem we all have at the beach.

"What does a $300 bathing suit have that a $20 one doesn't? Does it magically keep sand from going in your butt?" she asked.