People who are born in the period of 21st December to 19th January are Capricorneans, which is another word for people born in the Capricorn period. These people are earth signs because they are ruled by Saturn, and like all earth signs, they are deeply grounded to nature and are quite practical. Most often, Capricornians are known to be the hardest workers among all the twelve zodiac signs. Some of the popular Capricornians who have left a dent in this world are Martin Luther King Jr., Michelle Obama, and Dolly Parton. The main Capricorn birthstones are garnet, lapis lazuli, and blue topaz.