Gemstone value of the stone. Some treatments are used widely because the resulting gem is stable, while others are not accepted most commonly because the gem color is unstable and may revert to the original tone. Heat can improve gemstone color or clarity. The heating process has been well known to gem miners and cutters for centuries, and in many stone types heating is a common practice. Most citrine is made by heating amethyst, and partial heating with a strong gradient results in “ametrine” – a stone partly amethyst and partly citrine. Aquamarine is often heated to remove yellow tones, or
William S. Stone William S. Stone General William Sebastian Stone (January 6, 1910 – December 2, 1968) was an American United States Air Force Major General and the third Superintendent of the United States Air Force Academy. His final assignment was as the air deputy to the Supreme Allied Commander Europe. Stone was born at Cape Girardeau, Missouri on January 6, 1910. After graduating from high school in St. Louis, he attended the United States Military Academy, and, upon graduation on June 12, 1934, was commissioned a Second Lieutenant. Upon completing flying training in October 1935, he was assigned to the 32nd Bomb