Diamonds are a guy’s best friend?

First he raided your grooming products. Then he usurped your aesthetician. And now, ladies, not even your jewelry box is safe.

Today, men are buying themselves bracelets, rings and pendant necklaces with increasing frequency and wearing their bling with a confidence and flair heretofore unseen in the Western world, according to fashion experts and industry observers.

“From an industry perspective, men’s jewelry has been one of the real stars of the last couple years,” says Brian Nohe, president and chief operating officer of Spectore Corp., a fine jewelry manufacturer. “Men are spending more time grooming themselves. That carries over into the men’s jewelry market.”

So much so that insiders estimate the industry has seen a 20% growth in men’s jewelry just in the last few years. Designers such as David Yurman have started expanding existing men’s jewelry collections, and many manufacturers, most of whom had focused solely on women, have for the first time launched lines aimed at men.

“In 2005, there must have been at least 20 new brands added in men’s jewelry,” says Jeff Prine, executive editor of Modern Jeweler magazine.

Hip-hop mogul Russell Simmons is the latest to join the fray, recently launching the Simmons Jewelry Co. Men’s Collection. The collection of bracelets, chains, pendants, rings and diamond earrings has an edgy, urban feel, made of alternative materials such as rubber and steel.

Already the brand is a favorite among the celebrity set. Sean “Diddy” Combs wears one of Simmons’ rubber bracelets in his latest music video, “Nasty Girl”; actor Adrien Brody wore one to the “King Kong” premiere.

Simmons says he knew the line would take off. Pieces are sold at Macy’s department stores for an average price of about $400.

“I’m in the fashion business. That’s my job,” says Simmons, a collector of fine watches. “I hang out with a bunch of rappers and kids.”

But male-oriented jewelry isn’t strictly for the diamonds-in-both-ears hip-hop crowd or the fashion-experimental young.

From the basketball court to the boardroom, men of all ages, lifestyles and income levels are finding themselves more inclined to throw on a little something shiny.

“There are different segmentations of men [buying jewelry]. Some men are more of the Ralph Lauren set, penny loafers and blue blazers,” says Nohe, whose company is behind the new and popular Edward Mirell brand of men’s jewelry. “Then you have the Wall Street business types.... It has really taken hold in all segments of the market.”

Greg Nichols of Timonium was never a jewelry lover. But when he recently stumbled across a unique-looking bracelet made of braided black titanium, a new fan was born.

“I was looking for a piece of jewelry for my girlfriend, and this thing just jumped out at me,” says Nichols, 47. “It was just minimalist and masculine, and I just had to have it.”

Nichols, a contractor, says the purchase initially gave him pause. What would his girlfriend think? What would the guys at the development sites say?

As it turns out, Nichols’ girlfriend loves the bracelet. And his co-workers haven’t razzed him at all about his beautiful wrist wear.

“One of my buddies is going to get one similar to it,” Nichols says.

Word-of-mouth has helped fuel this upswing, which industry insiders say is more the start of a new era in jewelry than a fad.

Athletes and celebrities’ obsession with “ice” and “bling-bling” filtered from the urban to the suburban market and created a demand for jewelry for the mainstream man, says Mary Moses Kinney, director of the Independent Jewelers Organization, which represents 850 independent jewelers in the United States and Canada.

“These super-masculine guys are saying, ‘Jewelry’s cool, and I’ll show you why because I’ll wear it.’ So as a result, men are thinking, ‘Hey, it’s OK for me to wear this.’ ”

And therein may lie a benefit for the ladies in their lives.

“I think that this will actually help women,” says Moses Kinney. “What I think will happen is that men will develop a better comfort level about purchasing jewelry and won’t feel so intimidated by the whole jewelry buying experience.”