By leaps and bounds Chessex is the largest dice manufacturer in the RPG gaming industry. If you go to any game store or look through any RPG gamers dice collection, the vast majority of their dice will be Chessex dice. Chessex manufacturers all manner of polyhedral RPG dice, from your basic opaque dice to translucent and speckled to their premium dice styles. The most popular Chessex dice are certainly their signature dice (premium dice) including the gemini and scarab dice series.
Chessex dice are all very high quality RPG dice, and all of the Chessex dice styles are available in various dice sets. In addition, Chessex now makes the Game Science precision dice, only they have advanced the dice manufactuing technology so that these sharp-edged precison dice can now be manufactured with printed numbers (before Chessex came along, the numbers were just inset in the dice, and weren't colored, due to manufacturing reasons).