It's the first official day of summer, and what better way to kick off the season of triangle string bikinis than with a step-by-step guide on how to spot a boob job?

Allure saved us all the inevitable "are they or aren't they?" wonderings by calling up Los Angeles plastic surgeon Steven Teitelbaum to get the 411 on how to spot fake breasts. So before you hit the beach, familiarize yourself with these tips.

• The Gap: A major giveaway to a pair of implants is the wide, bony gap in between the breasts. According to Teitelbaum, many surgeons put in bigger implants in an attempt to mask said gap, but this ends up making it look even worse.

• The 360 Border: If you're seeing a defined 360-degree border around the edges of the breasts, they're faaar from natural. If you have enough time, picture the right breast as a clock. If it's natural, it should only have a border from about four o'clock to eight o'clock.

• A Lack of Gravity: The hoards of women lying out and tanning make summer prime implant-spotting season. Why? If a woman is au natural, while lying down her breasts will fall slightly to either side. Large implants, however, will remain upright and straight.

• An Even Profile: When viewed from the side, fake breasts look as full on top as they do on the bottom. Natural breasts, on the other hand, tend to have more volume in their lower half, once again, thanks to our good friend, gravity.

• Downward Pointers: Most normal nipples point slightly up or straight ahead. Implants, especially ones that are too big, usually cause nipples to tip downward.