Yorkshire Philosophical Society

Event Information

Carbon-based Gems, Carbon-based Consequences

Sarah Steele, Director Whitby Jet Works and Curator of Jet at Whitby Museum

Diamonds promise forever love, but the first synthetic ‘forever’ belonged to jet. When Victorian demand for Whitby jet outpaced supply, the quest for a substitute led to plastic. Today, lab-grown diamonds are marketed as sustainable, but history warns us: synthetic gems rarely disappear when their beauty fades. Sarah Steele, Director of The Ebor Jetworks, explores why some forevers are measured in catastrophe, not in carats.

Sarah Caldwell Steele—Curator of Jet at Whitby Museum—fell in love with Whitby jet at seven. With over forty years of commercial lapidary experience, a geology degree, and Fellowships of the Gemmological Association, she is now the leading authority on jet. She is also a PhD researcher at Durham University developing new ways to identify and classify ancient carbonaceous materials in the archaeological record.

7pm in the Tempest Anderson Lecture Theatre in the Yorkshire Museum on THURSDAY 11 JUNE 2026.

An event for York Festival of Ideas – free event tickets from May 1st at:

https://yorkfestivalofideas.com/

Member’s report:

Sarah Steele is an expert in black gemstones whose PhD will be the first research into jet for nearly 100 years. A devotee of jet, she also runs Ebor Jetworks Ltd. in Whitby.

Jet is fossilised wood from the Jurassic period, impregnated with bitumen. “Jetonised” means that the vegetable shape has been retained and the name jet is a contraction of this but has no specific definition.  In the Mesolithic period, jet was considered magical because of its physical properties including its ability to be polished to a mirror-like lustre; it rings when struck, retains a negative static charge for a long time when rubbed with wool and it burns with green smoke.

Since the early Bronze Age, jet has been used for jewellery and across the Roman Empire was set with elephant ivory, symbolising the north and south extremes of the Empire. The Saxons believed that jet protected against many misfortunes such as thunderbolts, demonic possession and sorcery and was commonly found in medieval graves. In the reign of Queen Elizabeth I, rosaries and crucifixes were banned and a person found with jet items could be charged with treason. However, in King James I reign, a “Demonology” text suggested that all should guard against witchcraft so the popularity of jet increased and saw a boom in the 19th century when the Empire was mourning the death of King George IV. This led to a massive rise in the number of factories so coastal jet mines began to run out. Various substitutes were invented, culminating in 1907 with Bakelite, a thermosetting plastic which could be fashioned in ways similar to jet. Parallels were drawn between the current state of the diamond industry with its challenges from artificial diamonds, and the jet industry, although jet could be considered to be more natural and ethical.

Rosemary Anderton