As has been mentioned here before, imitating tortoiseshell on furniture has been achieved with varying degrees of realism down the centuries. The tortoiseshell backgrounds of japanned work often consisted of nothing more complex than random daubs of opaque black paint on an opaque coloured (predominantly red) ground, while original standalone testudinal painted finishes usually exhibit more artistic accomplishment. As with grained wood finishes, a proportion of absolute painted tortoiseshell finishes developed into an art form in its own right.
All the same, great strides were made by a number of artists to more accurately recreate natural tortoiseshell, which process involved laying metal foil (brass, gold or silver) on a substrate over which were laid numerous coats of coloured translucent varnish.
Sometime after 1681, Venetian born Joachim Becher developed a method of extracting tar from coal which he used (in conjunction with asphaltum and pitch) to tint varnishes for simulating tortoiseshell.
The ‘projecting genius’, Thomas Algood, (d. 1716), a Northamptonshire Quaker, applied brown lacquer [presumably asphaltum- or tar-based] over irregularly shaped pieces of foil to imitate tortoiseshell.
John Baskerville of Birmingham took out a patent for his simulated tortoiseshell in 1742, describing it as “An imitation … which greatly excells Nature itself both in Colour and hardness.”
The finish on my William and Mary chest of drawers adhered to the practice of building up layers of contrasting paint and translucent varnish to simulate tortoiseshell; however, this girandole attempts to replicate the work of these latter craftsmen using asphaltum and other naturally tinted varnishes over metal foil.
Due to the complexity (and presumable cost) of foil-and-varnish tortoiseshell, it was normally reserved for smaller, more intimate objects for the bed chamber and parlour.
While my chest’s distinctive painted finish displays considerable depth and a charm all of its own, it cannot compete with the naturalistic chatoyance of the girandole’s finish. It’s quite mesmerising and virtually impossible to describe in words or portray in pictures. In the early morning sunlight, the deep scarlet flickers to searing yellow with the merest shift of the body.
The frame and looking glass have been sympathetically aged.
I’m just awaiting the arrival of the candle arm castings to complete the girandole.
 HUTH, Hans, Lacquer of the West – The History of a Craft and an Industry 1550-1950, The University of Chicago Press, Chicago, 1971, pp. 111-112.
 JONES, Yvonne, Japanned Papier Mâché and Tinware c.1740-1940, Antique Collectors’ Club, 2012, p. 43.