Dragon Colors

Valhalla is a canon Weyr, meaning there are no crazy colors like purple and rainbow. We have only the traditional colors (not including white), which are as follows:

Gold
38-42 feet long
Impresses female only
Gold dragons, or queens, are the largest and rarest of all dragons. All lesser colors will answer to a queen, even going against the wishes of their riders to do so. Gold dragons also are the only females that can lay eggs, but this prevents them from chewing firestone, so golds and their riders make up a special Queens' Wing. Weyrwomen always ride gold, and the rider of the most senior queen is the Senior Weyrwoman.

Bronze
35-38 feet long
Impresses male only
Bronze dragons, the largest of the males, make up only five percent of all dragons. They have the most endurance after the queens and can last for an entire Threadfall, which is why their riders often become wingleaders. The rider of the bronze who is able to catch a queen in a mating Flight becomes the Weyrleader and is in charge of all military operations against Thread. Bronzes may also fly greens if there are no golds.

Brown
30-35 feet long
Impresses male only
Brown dragons are only slightly smaller than bronzes and as such may dare to fly a junior queen. Their riders may become Weyrleaders, wingleaders, wingseconds, or any other position usually dominated by bronzes... if they are ambitious enough. Browns are extremely valuable in the Wings for their ability to fly long and fast, even lasting out an entire Fall with the bronzes.

Blue
25-30 feet long
Impresses male, rarely female
Blue dragons are the smallest and fastest of the male dragons and are unable to last an entire Fall; thus, they fight in shifts. They are much more maneuverable than larger dragons, and often protect them from dangerous clumps of Thread. Blues only fly greens but may Impress men or women; female blueriders are always homosexual. Blues make excellent Search dragons.

Green
20-25 feet long
Impresses male or female
Green dragons are the smallest and fastest of all dragons. Because they have the least endurance, they may only last a fraction of a Fall, but work with the blues to get hard-to-reach bits of Thread. They are female, but unable to clutch as they chew firestone--which is just as well because they Rise every two months! Greens impress both men and women; male greenriders are always homosexual. Greens make up about half of all dragons.

Here is a pretty good diagram of how big the dragons are compared to each other and to their riders. Please note that while the DLG states that the dragons are measured in meters, Anne McCaffrey clarified that they are to be measured in feet.