Hanneman applied his unique perspective to the study of gemmology and, through his undeniable intellect, revolutionised many areas of the gemmological field.
An accomplished scientist, Hanneman completed his undergraduate degrees at the University of Illinois, Urbana-Champaign and his PhD in Organic Chemistry at the University of Nebraska.
Hanneman worked as a research analytical chemist for the DuPont Research lab, the Standard Oil/Chevron Refinery, and the Kaiser Center for Technology. Gemmology was introduced to Hanneman by his father, a gemstone cutter, and remained a passionate hobby throughout his life.
Hanneman became concerned about the cost of pursuing a formal gemmology diploma and set out to make gemmology more widely accessible.
He tackled this issue with practical solutions, including designing and producing the Hanneman Gemmological Instruments, including the polariscope and dichroscope pocket kits and a range of gemstone filter kits. Based on their composition, structure, and impurities, gemstones absorb, reflect, and transmit light differently. Filters enhance these differences, making them easier to observe.
For example, the Chelsea Filter, which transmits deep red and some yellow-green light, detects chromium and cobalt content in gemstones and often identifies synthetic or treated stones, such as natural emeralds from green glass.
The Hanneman instruments were made as cost-effectively as possible, keeping prices down and making them affordable for anyone interested in gemology.
Hanneman was a prolific writer on the subject of gemmology, authoring several books, including: Guide to Affordable Gemology, Determinative Gemology – A Key to Arem’s Color Encyclopedia of Gemstones, and Pragmatic Spectroscopy For Gemologists.
Among his other titles are: Naming Garnets: Sinkankas Symposium 2008, Naming Gem Garnets, Guide to Affordable Gemology and Determinative Gemology: A Key to Arem’s Color Encyclopedia of Gemstones, as well as additional guides.
His background in chemistry offered a unique and insightful perspective on the subject. Hanneman developed his diamond cut grading system to make evaluating diamond cuts easier.
He called this system the Hannemen Diamond Cut Grading System, and it remains available for free at the International Gem Society (IGS) and Canadian Institute of Gemology.
Hanneman's vast knowledge of gemmology and his contributions to the field make his position as a 'self-ordained gemmologist' quite extraordinary.
Despite this unofficial credential, his dedication and knowledge of the subject were internationally recognised.
The Accredited Gemologists Association (AGA) twice honoured him with the Antonio C. Bonanno Excellence in Gemology Award.
“Dr. Hanneman has dedicated decades to providing gemologists with practical solutions to many of gemology’s big challenges,” said AGA president Stuart Robertson at the time.
The International Society of Appraisers also awarded him an Industry Service award.
In addition to his dedication to gemmology and impressive career in chemistry, Hanneman was a keen fly fisherman. He developed the Common Cent System to measure fishing rods, proving his innovative spirit and unquestionable intellect.
Hanneman has left an undeniable legacy in gemmology and is praised worldwide for his contributions and unique perspective.
Robert James, president of the International School of Gemology, summarised his contributions to the field as follows: "He was an iconoclast who simplified the concept of gem identification and made it more affordable and understandable for so many in the industry.”
Hanneman, who had been married for 65 years, passed away at 93. He left behind four children: one granddaughter and three great-grandchildren.
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