Blue is a primary color and many objects in nature have a blue color, including cobalt compounds, the flames of burning sulfur, the sky and the ocean. In 1873, Levi Strauss and Jacob Davis applied for a patent for riveted waist overalls, which were the first blue jeans.
George Brandt, a Swedish chemist discovered cobalt in 1739 in his attempts to classify compounds used to turn glass blue. Until his discovery, bismuth received much of the credit for this color in glass products. Humans have used cobalt compounds to give a blue color to ceramics, pottery and tile for centuries.
While most people think of molten lava as red, Popular Mechanics reports that the lava of Indonesia's Kawah Ijen volcano is blue after sunset. The blue color is due to sulfuric acid that leaks into the volcano. The burning acid gives off the characteristic blue color of burning sulfur.
During the California Gold Rush, a miner's wife asked Jacob Davis, a tailor from Reno, to make her husband a pair of workpants to withstand the rigors of mining. Davis used rivets reinforce these denim pants at the stress points. Davis partnered with Levi Straus to apply for the patent. While denim pants were nothing new, the addition of rivets made the invention worthy of a United States Patent.