Category Archives: Venetian Chalcedony and Adventurine Glass Bowl

Up close and personal 

microscopic investigation of a Venetian Opalescent Glass Bowl

After having spent several weeks researching my Illuminating Objects glass bowl, I got the chance to see it in the flesh again for a bit of a scientific investigation. I felt quite at home visiting a lab and using a microscope, but seeing the Courtauld’s conservation labs, filled with paintings hundreds of years old, was a different experience!

I had come across an article published in 1894 by a mineralogist, Henry Washington, who was a descendent of George Washington. His interest in minerals led him to Murano, in Venice, the centre of the glassmaking industry, as this was where man-made imitations of natural stones were being developed. Washington managed to procure some samples of aventurine, ‘through the kindness of Signor G. Boni of Rome’ – both a prime example and a failed attempt – for his investigations.

Washington says that aventurine was one of the first ever substances of a mineralogical nature (that is, its structure) to be studied under the microscope. So, 121 years after Washington peered down the microscope at a chunk of aventurine, I did the same to the aventurine samples in my bowl.

The following pictures are taken at 120x magnification:

Looking closely, you can just make out individual crystals of copper, which give the aventurine its sparkle. They form triangular and hexagonal crystals, something noted by Washington back in 1894. Unfortunately, Washington was slightly better equipped than the Courtauld in terms of his microscope’s power, and was able to see up to 200x magnification, while 120x was as close as we could get (Such high magnification is unnecessary for the work the Courtauld needs the microscope for, but is rather low for today’s capabilities).

Washington was able to make these detailed drawings of the crystals of copper he saw at 200x magnification.

While we were looking at the bowl under the microscope, I noticed a peculiar phenomenon of chalcedony glass. I had read once or twice in my research about a ‘red glow’ that was characteristic of chalcedony glass when a light was shone on it, but it hadn’t been described any further. Where the spotlight used to illuminate the bowl for the microscope was aimed, the glass beneath it shone red! With a bit of rearranging of the light source, we captured these amazing images of the glowing bowl.

Getting a closer view of the bowl under the microscope has really let me see the object in a new light (pun intended!). This little bowl certainly has more to it than first meets the eye, and as I approach the end of the project I am eagerly awaiting its installation in the Courtauld Gallery.


three people working on the installation of the venetian glass bowl in the Courtauld's gallery

The Courtauld’s newest instalment is finally ready and has now been sitting proudly on display for over a week. The Venetian bowl (I have become accustomed to calling it ‘my’ bowl) is small but a lot of time, consideration and work from many people has gone into its display. From Sacha Gerstein’s curatorial eye to Graeme Barraclough’s experience as a conservator, Colin Lindley’s mount-making efforts and many more, the one tiny bowl had a lot of fantastic people working hard behind it, including my own research!

I arrived bright and early on a beautiful sunny day at The Courtauld on the day of the installation. Due to works being carried out on the galleries lifts, the glass case had to be physically carried up the flight of stairs to its new home. However, this was luckily the last hurdle the project had to make before being completed.

After some adjustments to the mount, and the application of new lettering and positioning of text labels, it was time for the bowl to be installed. The chalcedony glass that makes up the bowl has a fascinating quality of glowing bright red when a bright light is shone directly at it. Because of this, we wanted to get the lights in the case at just the right angle to produce some of this for visitors to see.

Another difficulty was how to angle the bowl. The inside of the bowl has a milky pale green colour, nowhere near as beautiful as the swirling patterns on the outside, which is much more interesting to look at, and relevant to the bowl’s history. This faced us with a small problem, because short of displaying the bowl upside down (in which case it would cease to look much like a bowl), one side of the cabinet was going to have a view of the inside of the bowl.

In a last-minute change (quite literally, just minutes before the glass hood was secured into place!) we decided to try turning the bowl round by 90 degrees. It sounds silly, but having the bowl side-on wasn’t something that had occurred to us! This way, both ‘viewing’ sides of the case, where the text panels are, get a brilliant view of the bowl’s exterior.

And with that, we ushered ourselves out of the gallery as the first members of the public arrived for the day.

The whole process of completing the Illuminating Objects internship has been eye-opening to a whole world I had never truly contemplated before. It has been hard work, but also fascinating, and immensely rewarding.

Thank you to everyone at The Courtauld (and beyond) who has given their time and assistance to this project. Special thanks to Sacha Gerstein for her guidance and expertise, and for giving me the opportunity to take part.

Decisions Decisions 

two female students examining the adventurine bowl

It is now time to select my object to illuminate!

Perhaps embedded with a genetic interest for ceramics, I had initially thought about selecting some albarelli, earthenware pharmacy jars, some of which are already on display in the Courtauld. These objects were ceramic, something I had a childhood relationship with, and had a clear link to science – I had even studied pharmacology as part of my undergraduate degree.

Maybe it was because the link was just too clear, but, already a little out of my comfort zone in an art gallery, I thought I might as well jump in the deep end with a beautiful Venetian glass bowl.

I can admit that I was initially drawn to the bowl for shallow reasons – it is beautiful glass swirling with browns and greens and small inclusions of deep caramel sparkles – rather than knowing anything at all about glassware. In fact, I was completely in the dark, but armed with a folder on the object’s history and details, I began working my way into writing on Venetian glass. I soon discovered the names of the two techniques that gave the bowl its stunning aesthetic appearance – calcedonio, which is a type of glass that gives swirling colours, and aventurine, the golden sparkles.

As my research continues, I hope to be able to enlighten myself about the processes of glassmaking, as well as the culture surrounding the craft in the 18th century. Eventually, I will be able to call myself an expert on this very small area of art history, and look forward to sharing this newfound knowledge with the visitors of the Courtauld Gallery.

Introducing Eleanor

Eleanor Magson standing in front of the venetian glass bowl in the Courtauld's galleryThe Courtauld Gallery is one of the last places I would have guessed I would be working, if you had asked me a few years ago. At this time, a pharmaceutical or neurological laboratory would have been more in line with my expectations. But, after three years of degree study in Biomedical Science, I decided life at the lab bench wasn’t for me and I turned myself over to the humanities for a degree in Science Communication, in order to share my love for science with the public.

As the child of two potters, my journey down the science pathway was a bit of a breakaway from my artistic side, but it wasn’t long before I became interested in communicating science through art, as a way of reconciling my two (often opposing) interests.

It was soon into my Masters in Science Communication at Imperial College that the opportunity to apply for the internship at The Courtauld arose. Although I had done a piece of research on the use of enriching the teaching of science with arts and humanities, I had no experience of enriching art with science.

The Courtauld, like all galleries, provides information on the historical context to their objects and paintings, which can often include social, religious and political context, but science is not something seen within many art galleries.

I wanted to bring out not only the technical science of the creation of my selected object, but also the effect of the state of the scientific world of the time on the object. Scientific discoveries fuelled how we looked at the world, often having huge influences on the development of societies.

Keep an eye on the Gallery blog to find out more about my Illuminating Objects project.