Only around 3% of the turquoise on the market now is completely natural. Due to the decline in natural turquoise discovered in mines across the world, it is extremely difficult to find completely natural and untreated turquoise accessible to buy in beads or cabochons for jewelry manufacturing. Most natural turquoise is stained some color or another when it is found. The color may be blue, green, red, or brown. The rest of the market share for turquoise is made up of synthetics. Synthetic turquoise is manufactured by heating mineral deposits in a furnace to very high temperatures (1400 degrees Celsius or 2350 degrees Fahrenheit) and pouring molten metal into molds. Once cooled, these rocks have been transformed into beautiful gems with colors that can match or surpass those found in natural stones. Synthetic turquoise was first created in 1872 by an American named Harvey Hubbell. He invented a process called "photo-chemical treatment" which involved taking photos of pieces of rock jewelry material and then painting over the images with chemicals. This process changed the color of the turquoise from its original blue to other colors such as green, red, and brown. In 1937, another innovation came about when two brothers named George and Harry Winston developed wire wrapped jewelry pieces. Before this time, all jewelry was handmade and most items were strung together with leather or silk threads.