A wonderful pair of 18ct gold cufflinks set with four cabochon rock crystals. They have been engraved in the reverse with four Irish terriers. A reverse crystal intaglio is a rock crystal cabochon with an intaglio carved into the flat back. The intaglio was also painted realistically with oils so, that when viewed through the top, the image appears three-dimensional. Finally, the back was sealed in order to preserve the painted areas. The technique originated in Belgium c. 1860 and is attributed to an artist named Emile Marius Pradier. This technique was also practiced in England by Thomas Cook and his descendants who made crystals for Lambeth & Co.
Production of a reverse crystal intaglio begins with the mining and cutting of fine rock crystal from Brazil or Madagascar. A well-formed cabochon is the key to a beautifully made reverse intaglio and the tedious process of hand polishing it to perfection had to be completed before the design work could begin. A watercolour of the image was painted on the underside of the cabochon and an oil and diamond dust mixture was used along with up to 250 scribing tools to carve the design into the interior of the crystal "...the deeper the carving the more pronounced trompe l'oeil effect." Once the carving was established the painting process began with extremely fine brushes and paint working in reverse to create incredibly detailed images.
The motifs most commonly found are sporting themes - horses, dogs, foxes and birds. This relatively secret process passed through family members, so keeping it exclusive and expectations of quality were very high. They remained in fashion until poorly made glass and plastic imitations flooded the market c. 1920s.}