Dr. John Emmett

Dr. John Emmett is one of the world's foremost authorities on the heat treatment, physics, and chemistry of corundum. He is a former associate director of Lawrence Livermore National Laboratory and a co-founder of Crystal Chemistry, which is involved with heat treatment of gemstones.

Articles by Dr. John Emmett

Impurity Ions and Gemstone ColorsPhoto by <a href=https://www.gemsociety.org/author/johnemmett/"https://www.flickr.com/photos/42200412@N03/">Géry Parent</a>. Licensed under <a href=https://www.gemsociety.org/author/johnemmett/"https://creativecommons.org/licenses/by-nd/2.0/legalcode">CC By-ND 2.0</a>." src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" decoding="async" data-nimg="responsive" style="position:absolute;top:0;left:0;bottom:0;right:0;box-sizing:border-box;padding:0;border:none;margin:auto;display:block;width:0;height:0;min-width:100%;max-width:100%;min-height:100%;max-height:100%;object-fit:cover;object-position:50% 50%"/>

Impurity Ions and Gemstone Colors

How do gems likes rubies and red beryls get their red color? Learn the role impurity ions play in the...
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