In 1877, French chemist Fremy used pure aluminum oxide powder, potassium carbonate, barium fluoride and a small amount of potassium dichromate as raw materials, melted them in a crucible at high temperature for 8 days, and obtained small particles of ruby crystals, which was the beginning of artificial ruby.
In 1900, scientists used a method of adding a small amount of chromium oxide, Cr2O3, at a weight ratio of 0.7% after melting aluminum oxide to produce 2g~~4g of ruby. Now, rubies and sapphires as large as 10g can be produced.
In 1885, some high-quality artificial rubies appeared in Geneva, Switzerland. It is said that they were made of natural ruby fragments, potassium dichromate, etc., which were melted at high temperature to enhance the red color. They have the same properties as natural products. However, the real realization of artificial gemstones and large-scale production is attributed to the French chemist Verneuil. Verneuil invented the flame melting method in 1891 and used it to try to produce artificial gemstones. After the success, he used pure alumina to test. In a high-temperature muffle furnace, an inverted hydrogen-oxygen blowpipe was used to test. Pure alumina powder containing a small amount of chromium oxide slowly fell into the flame to melt, and dripped on the base to condense and crystallize. After ten years of hard work. Verneuil officially produced artificial rubies in 1904. Later, the flame melting method was gradually improved, and the rubies produced were almost indistinguishable from natural products. This method has been used until modern times and is still the main method for producing artificial gemstones in the world. It is called the "Verneuil method". Now, it only takes a few hours to produce ruby rough stones of more than 100 carats. The artificial corundum crystals with inverted pear or carrot shapes are pure in texture and even more transparent than natural products, which has huge economic benefits. The modern Vernet method can not only produce rubies from light pink to dark red, but also sapphires of various colors, and even rubies and sapphires with starlight, which is really amazing.
