Ulrika D'Haenens-Johansson
Gemological Institute of America (GIA), New York, USA

1pm - 2pm, Monday 3rd December
Materials & Analytical Sciences (MAS 2.06)

Traditionally, when people think of diamonds as a gemstone they visualize the classic colorless round brilliant. However, through the incorporation of point or extended defects in the crystal lattice, the full rainbow of colors can be found in natural diamonds. These rare diamonds, termed “Fancy Colored” in the gem trade, often command higher per carat* prices (up to $3.3 million per carat) compared to their colorless counterparts, generating great excitement at auctions and in the news. These colors can also be produced artificially through treatment of selected natural or laboratory-grown diamonds. By studying the structure, formation and destruction of color producing defects in diamond through a range of spectroscopic techniques it is possible to separate natural, treated and synthetic diamonds, maintaining transparency in the trade. In this seminar we will review some of the key color-producing defects in both natural and synthetic diamonds and see examples of how careful defect engineering can be used to produce attractive fancy colored materials.
*1 carat = 200 mg

1-2pm Monday 26^th November
Materials & Analytical Sciences 2.06

Nitrogen is the most commonly identified impurity in diamond. When diamond is annealed with sufficient temperature, various species become mobile and single nitrogen substitutional atoms aggregate into larger complexes. Understanding and controlling this process is significant to engineering defects into diamond, such as the nitrogen-vacancy centre, as well as understanding the differences between natural and synthetic diamond. Irradiation prior to annealing increases the aggregation rate; this is caused by both vacancies and interstitials mediating the mobility of nitrogen. In this presentation I will talk about the migration of vacancies and interstitials and their role in enhancing the aggregation process. I will highlight differences between aggregation in natural, HPHT and CVD grown diamond. Finally, I will explain how these differences can be used to effectively distinguish natural from synthetic diamond and their use in De Beers’ screening instruments.

2pm - 3pm, Wednesday 21st November
Materials & Analytical Sciences (MAS 2.06)

Although its optical properties are those most often cited and even revered, diamond also possesses characteristics that extend its field of application well beyond luxury jewellery.

This presentation focuses in particular on the electronic properties of diamonds, thanks to which Micron Semiconductor manufactures radiation sensors for applications as diverse as particle physics, space exploration, energy or medical diagnostics.

After an introduction on artificial diamond and its various uses, we will explore the steps involved in manufacturing a sensor and examine current and future applications in this sector.

Gloria Zhao (Cohort 3) and Phil Diggle (Cohort 1), along with Prof. Mark Newton, were invited to attend the 2018 Gemological Institute of America (GIA) International Gemological Symposium. Phil delivered a talk on how to image diamond down the diffraction limit using confocal photoluminescence microscopy and how this has revealed new insights on the growth of synthetic diamond. Gloria gave a talk on phosphorescence and thermoluminescence of diamond. Both talks were very well received by the 200-plus audience members in the morning session of the first day of the symposium. The remainder of the first day saw talks from leading researchers in their field of diamond science from the synthesis, characterisation and the geology of diamond.

2-3pm Wednesday 7th November
Materials & Analytical Sciences 2.06

Chemical vapour deposition (CVD) is a well-established and robust method of diamond synthesis. The versatility of CVD enables a high degree of control over the formation of point and extended defects in diamond. This allows a range of single crystal and polycrystalline diamond grades to be engineered for specific applications. As an optical material, CVD diamond can provide solutions for extremely demanding applications. In this talk we review the key optical properties of CVD diamond and how these can be influenced by synthesis conditions. A range of optical applications will be presented, which harness diamond’s properties to enable performance beyond the capability of conventional optical materials.