The term designer label refers to clothing and other personal accessory items sold under an often prestigious marquee which is commonly named after a designer.
The term is most often only applied to luxury items.

Some of the most famous designers:

Christian Dior: an influential French fashion designer.
Dior almost singlehandedly restored Paris as the capital of the fashion world. He then went on to revolutionize the fashion industry.
His famous clients incuded, Ava Gardner, Marlene Dietrich, Rita Hayworth, Margot Fonteyn, Princess Margaret and the Duchess of Windsor.

Jacques-Theodule Cartier: was one of three sons of Alfred Cartier and the brother of Pierre Cartier and Louis Cartier.
Jacques took charge of the London operation of Cartier in 1909.
Louis Cartier: created the Santos wristwatch, which was also the first wristwatch made for men.
Pierre Cartier: In 1902, Pierre opened and began to manage the London Cartier store and in 1906, he opened the New York store, moving it in 1917 to the current location of 653 Fifth Avenue.

Chanel: a prominent Parisian fashion house specializing in luxury goods.
Founded by Coco Chanel, the Chanel label has become one of the most recognized names in luxury and haute couture fashion.

Gucci: an Italian iconic fashion and leather goods label.
The House of Gucci was founded in 1921 by Guccio Gucci.
Gucci is the biggest-selling Italian brand in the world.

Ralph Lauren: an American fashion designer and business executive.
He is most notable for his Polo Ralph Lauren clothing brand.
Lauren's empire was founded in 1967, after he opened his first ever tie shop, with no formal design training.

An interesting biography of Ralph Lauren can be found at: Biography

For mens jewelry try: Jewelry For Men.