John Koivula

  • Book Review | Photoatlas of Inclusions in Gemstones, Volume 2 | Lotus Gemology

    Photoatlas of Inclusions in Gemstones, Volume 2 • A Book Review

    Gübelin, Eduard J. & Koivula, John I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Opinio Publishers, Basel, Switzerland, 830 pp. ISBN 978-3855040957

  • Inclusions in Gemstones | Hyperion Literature Sources

    Hyperion • The Literature of Inclusions in Gemstones

    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.

  • Ruby & Sapphire (Corundum) Inclusions | The Lotus Gemology Crystal Registry

    Corundum Inclusions • A Crystal Registry

    Solid inclusions have been used by gemologists as a means of determining origin. While there is a great deal of overlap from one source to another, there are also important differences. For example, while apatite has been identified in sapphire from Madagascar, Myanmar and Sri Lanka, apatite has never been identified in sapphire from Kashmir. Thus the purpose of this article is to give a full listing of solid inclusions in gem corundums from around the world, with each occurrence fully referenced. This is provided with the goal of making origin determination of ruby and sapphire more accurate.

  • Ruby & Sapphire Books | Collecting the Literature of Corundum | Hidden Treasure

    Ruby & Sapphire Books • Collecting the Literature of Ruby & Sapphire (Corundum) • Hidden Treasure

    A discussion of the literature of ruby and sapphire (corundum), with particular emphasis on the most collectible books covering ruby and sapphire around the world.

  • Spinel Inclusions | An Exercise in Aesthetics

    Inclusions in Spinel • An Exercise in Aesthetics

    To the jeweler, spinel is famous for its vivid colors. But for the gemologist, this gem is unlike any other. Its extreme hardness allows a fine polish. Couple this with single refraction, which eliminates the image blurring found in most other gems, and a varied landscape of inclusion subjects, and the result is an unparalleled canvas of delight for the photomicrographic artist.