Polychrome de Courseulles is a French lace originating from the Normandy coast in France. It appears around 1896, around the time that Chantilly lace (a black silk lace) was popular.
Polychrome is a silk lace, made with a very fine highly twisted ground thread and multi-colored threads in the decorative areas. The ground thread is usually a blonde color (a natural slightly off-white color), or black. The colored threads are usually not twisted very tightly, and often are strands of multiple colors, creating a combined color.
There are few books available on this lace. Claudette and Michel Bouvot are the primary authors. Dentelles Normandes - Polychrome de Courseulles(2001) is out of print; it is in French with a separate English translation. Polychrome de Courseulles - 9 Modeles (2004) is still available, as is Dentelle Polychrome de Courseulles sur la Route des Dentelles Normandes (the latter by Jean-Claude Brulet).
For anyone who is a fan of color, this is a lovely lace to see and make. Some samples can be seen at http://blondecaen.chez-alice.fr/esom.htm