Gübelin, Eduard J. & Koivula, John I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Opinio Publishers, Basel, Switzerland, 830 pp. ISBN 978-3855040957
The Gübelin Foundation (2014) The Eduard Josef Gübelin Story: The Art and Science of Gems. London. Gübelin Group, Lucerne, and Unicorn Press, 306 pp., illus., hardcover, ISBN 978-1-91006-540-2
In 1878, the noted Austrian mineralogist, Gustav Tschermak von Seysenegg [1836–1927], was the first to properly identify silk in corundum, finding it to be composed of the mineral rutile (TiO2). An English translation of his landmark paper is included, along with the original German version.
For those who wish to explore the literature of inclusions in gemstones further, we have selected the following articles and books that are of particular merit. Most of these are cited in the Lotus Gemology Hyperion Inclusion Database, but are listed below in a more convenient summary format. Many of the links will allow you to download a PDF copy of the original article.