2018 AGA Tucson Conference

A day of gemological insights

Photos...

Determining Emerald Origin - Changing what we learned in school
Andy Lucas/Shane McClure (bios)

Do We Speak the Same Language? - Dr. Çiğdem Lüle - An examination of current laboratory reports (SPOTLIGHT)

Madagascar: Sapphire Isle - Richard W. Hughes and E. Billie Hughes (SPOTLIGHT) - Important identifying features & preliminary results on related research *

A Massive Diamond Treatment Project - Dr. Thomas Hainschwang - First data, results and conclusions (SPOTLIGHT)

See New Colors - in a Rainbow of choices - for Natural Diamonds Created by HPHT- Sonny Pope - What's new in the market straight from the lab (SPOTLIGHT)

*Dr. John Emmett was not able to join us this year.

Attendees could select a Hands On Workshop or attend Nathan's presentation on gemologist's eye candy.

Gem recognitions with minimal equipment:

Visual Optics Revealed - Alan Hodgkinson - bio
A concept developed by Hodgkinson decades ago reveals what the optics of a gem can reveal without equipment. A chance to learn from the master before Alan retires from his Tucson visits.

Focus on Fluorescence – Exploring UV LW/SW Testing of Gems - Claire Mitchell, FGA DGA (bio)
Although not a diagnostic tool, UV is often the 'forgotten' essential of a gemological appraisers gem testing kit. Providing a portable quick solution for everyday gem id and testing. We explored, with discussion and hands-on, what fluorescence is all about – the circumstances where it can be most effective, its correct use and interpretation of the results – for colored gemstones and diamonds.

Distinguishing Black Materials - Sarah Steele (bio)
Often the bane of the gemologist are black gems and this workshop concentrated on quick visual cues to their identification, including the jet group, other organics and crystalline materials.

And in the main room
Through Your Eyes Only - Nathan Renfro (bio)
Attendees learned how the microscope helps us recognize treatments, origin, heat levels and other diagnostic features.

Spotlights!

Do We Speak the Same Language?
Çiğdem Lüle, PhD. (bio)

Gemological terminology has presented challenges for the gem trade since the beginning of modern gemology. Although rooted in mineralogy, in the broadest sense, gemology exists to facilitate trade. As a result, certain gemstone nomenclature is influenced by commerce and not by mineralogical standards. Research gemologists attempt to explore and resolve certain issues regarding gem names and treatment disclosure. However, recent gemological laboratory report language has revealed this to be a complicated subject with little consensus within the global gemological community. In most cases, meaningful and practical standards are overlooked or ignored. The lack of application of discernible standards has resulted in practices that can be not only confusing but also misleading to the gemologists, dealers and the consumer.

A Massive Diamond Treatment Project: First Data, Results and Conclusions
Dr. Thomas Hainschwang (bio)

Diamond treatments are a complex matter and particularly the distinction of radiation related naturally coloured diamonds from diamonds treated by irradiation and diamonds modified by HPHT treatments are very challenging. Even though a lot of data is available from research conducted at our laboratories and from scientific literature, the data is far from being complete. For this reason, a giant project has been launched by GGTL Laboratories Liechtenstein, through which a much more complete picture of the effects of treatments on the appearance and the defects of diamonds.

This project covers the characterization of diamonds of all types and colours treated by irradiation, annealing, HPHT and combinations thereof. It has been granted the AGA Research Grant of 10,000 USD per year in 2017. For this project, a significant quantity of untreated diamonds of all types and colours have been collected and pre-screened by infrared spectroscopy and luminescence imaging, and their properties have been collected in great detail. Besides visual techniques and optical microscopy, the analytical techniques used to characterize the diamonds include infrared and UV-Vis-NIR absorption spectroscopy, photoluminescence spectroscopy with 6 lasers (360 to 785 nm) and a range of UV excitations from the deep UV to longer UV wavelengths, and fluorescence imaging using various UV wavelengths from 210 to 400 nm.

All samples are currently being treated by the various treatment methods available, hence by irradiation by electrons and neutrons, heat treatment up to 1600°C, HPHT treatment from 1900 to at least 2500°C, and combinations of the treatment methods. After each treatment step all data recorded prior to the treatment will be recorded again. This project will produce a massive amount of very valuable data that will most likely give a precious insight into the effects of treatments on diamonds, more specifically the many defects known in diamonds. The most important data is expected from high resolution PL spectroscopy with a large array of excitation sources such as lasers and UV excitations.

See New Colors - in a Rainbow of choices - for Natural Diamonds Created by HPHT
Sonny Pope (bio)

High Pressure High Temperature (HPHT) processing is the core technology that makes permanent color changes possible. Nothing is added and nothing is removed from the diamond. Just like for ruby and sapphire, extreme heat can fundamentally improve the color of diamond. Through his applications of extremely high pressure processing, Pope explained how these changes occur and shared the latest options in what can be done with your brown or off colored diamonds. We also learned how to value the resulting colors.

Madagascar: Sapphire Isle
Richard W. Hughes and E. Billie Hughes (bios)

Over the past 25 years, no country in the world has produced as much fine sapphire as Madagascar. And yet this island's gems are still relatively unknown. In this presentation, Richard Hughes discussed the most important deposits from the deep south in Andranondambo, through the huge Ilakaka mining district and the wild jungle mines at Andrebabe and Moramanga (a.k.a. Sierra Leone).

Billie Hughes discussed the gemology of Madagascar sapphire and ruby, including the most important identifying features, and some preliminary results from a series of ongoing experiments on the heat treatment of Madagascar sapphire.