Pictured bellow-- GBD Estate Pipe Virgin Bent Billiard 508 from Smoker's Haven 
Pictured bellow-- GBD Estate Pipe Unique Magnum Sized Bent Champaigne Sitter
Pictured bellow-- GBD Estate Pipe Collector New Standard 9695
The premium lines of the GBD pipes are often found as an excellent value on the estate pipe market. Many of them are excellent examples of classic pipe shapes. The following list comprises the better grades in deciding order:
Pedigree, Pedigree I, Pedigree II, Straight Grain, Prodigy, Bronze Velvet, Virgin, Varichrome, Prestige, Jubilee, New Era, Prehistoric, International, Universe, Speciale Standard, Ebony, Tapestry, New Standard, Granitan, Sauvage, Sierra, Penthouse, Legacy, Concorde.
The following information is from a circa 1973 chart:
Virgin "Only the finest of closely grained briar is utilized for this exceptional pipe. Natural finish"
Century "A golden finish created to celebrate over a century of manufacturing the finest briar pipes."
New Era "The beauty of this pipe's perfect briar is accentuated by the richness of the 'take-off' dual finish."
Prestige "This pipe features a black handcut perspex mouthpiece which precludes discoloration and 'bad taste' after continual smoking. Only the finest of the fine-grained bowls are selected for this handsome matt virgin finished briar."
Prehistoric Perspex "The deep sandblasting sillhouettes the grain in bold relief. The crystal clear mouthpiece creates an attractive contrast to the deep dark finish."
A brief history of GBD
The company was founded in Paris France in the 19th century by Ganeval, Boundier and Donninger who were no longer associated with the company by the turn of the century. By the time they left the GBD name was well established and thus retained. In 1903 an additional factory was built in England and ran by Oppenheimer. The Paris factory moved to Saint-Claude in 1952. Since 1981 the majority of GBD pipes come from the English factory. At about that same time GBD merged with Comoys, since then all production for both GBD and Comoy comes from a single factory. 
This site has some excellent GBD Model information
G.L. Pease has a beautiful collection of older GBDs. Very interesting reading and pictures: