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
Gregory S. Stone the Pew Fellowship in Marine Conservation in 1997 and in 1990 won a postdoctoral award from the National Science Foundation for his work on marine science in Japan. In 1989, Stone received the John A. Knauss Marine Policy Fellowship and in 1986 the National Science Foundation and U.S. Navy Antarctic Service Medal. In 2013, Stone received the Wyland Foundation ICON Award, the NOGI from the National Academy of Underwater Arts and Sciences in 2015, and in 2014 was named the Boston Sea Rovers Diver of the year. Gregory S. Stone Gregory Schofield Stone (born 1957 in Boston, Massachusetts) is an