From about 1745, the porcelain manufactory at Vincennes (established in 1740 on the grounds of a former hunting lodge, east of Paris) marked its wares with the royal cipher – two interlaced L’s. This is usually painted in cobalt blue, either in overglaze enamel or in underglaze pigment.
A date-lettering system was introduced around 1754. Soon the factory’s decorators, particularly painters, began to mark their work. Throwers, moulders and répareurs, who fashioned or assembled objects, incised marks into the clay, which although largely unidentified, provide some evidence of authenticity.
For a detailed discussion of marks see Rosalind Savill, The Wallace Collection Catalogue of Sèvres Porcelain (London, 1988), vol. III, pp. 1081-1137.