‘Essex Crystal’ is a trade name given to a very specific form of glyptography (the art of gemstone carving) called a reverse intaglio. Essex crystal became popular in the mid 1800s and remained in demand until the early 1900s, where poorly made imitations in glass and plastic saturated the market.
Usually crafted using a dome of rock crystal, which is engraved on the flat back/ reverse before being painstakingly detailed with oil paints, so that when it is flipped over you see a beautiful 3D painting floating in the crystal cabochon. This differs from the traditional intaglio technique which utilises a variety of natural hardstones and is carved on the same side it is intended to be viewed.
A way to test the quality and age of your Essex crystal is firstly by the materials used, the more expensive examples are deeply carved and backed with gold foil and mother of pearl, whereas cheaper imitations may have the design merely painted onto the backing, with the crystal (or glass) merely acting as a quasi magnifying glass.
Confusingly the name Essex crystal stems from a centuries old misunderstanding. This technique was actually first perfected in England by Thomas Cook, who was influenced by Belgium gemstone carver Pradier, and then later succeeded by his own talented apprentice, Thomas Bean. However, around the same time there was a famed miniaturist to Queen Victoria, named William Essex. It appears that the public saw such wonderous miniature works and assumed it could come from no other person than the celebrated Essex, and so the name Essex crystal was born, despite it having nothing to do with Essex at all!
These are collectible pieces still treasured today, often depicting hunting memorabilia, nautical motifs or flora and fauna. Fine examples may be housed in elaborate settings whilst some simpler designs can be found in a timeless closed back collet.