French Blue - Something that really is French

In keeping with my research on terms or phrases that include the word "french" D. and I started talking today about "French Blue" - what color is it really? Where does the term come from? Is it really French? It is one of those colors that looks wonderful on everyone, warm but bright, soft but colorful, yet not overpowering. Looks good with black, brown, white, almost any other color.

So, a little research later and voila:

"French ultramarine ("French blue," Guimet's blue," "permanent blue," "synthetic ultramarine"):

Origin and History: Ultramarine is imitated nowadays by a process which was invented in France in the eighteenth century as a result of a prize offered by the French government. The raw materials of ultramarine manufacture are soda and china clay and coal and sulphur, all common and inexpensive materials. The process requires skill, is inexpensive, and the product is many thousand times less costly than genuine ultramarine prepared from lapis lazuli. The first observance of the substance was made by Goethe in 1787, when he noticed blue deposits on the walls of lime kilns near Palermo. He mentioned that the glassy blue masses were cut and used locally as a substitute for lapis in decorative work. In 1928, Jean Baptiste Guimet perfected a method of producing an artificial, and cheaper, ultramarine pigment.

Making the Pigment: Artificial ultramarine, also known as French ultramarine was made by heating, in a closed-fire clay furnace, a finely ground mixture of China clay, soda ash, coal or wood, charcoal, silica and sulfur. The mixture was maintained at red heat for one hour and then allowed to cool. It was then washed to remove excess sodium sulfate, dried and ground until the proper degree of fineness was obtained.

Chemical Properties: Because the particles in synthetic ultramarine are smaller and more uniform than natural ultramarine, they diffuse light more evenly. Chemically, the artificial ultramarines are not distinguishable from the blue particles of genuine lapis; you can only tell by the percentage of colorless optically active crystals, whereas the artificial is pure blue and free from diluting elements.

Artistic Notes: Synthetic ultramarine is not as vivid a blue as natural ultramarine. Synthetic ultramarine is also not as permanent as natural ultramarine. French ultramarine is light-resisting, but owing to the use of sulphur in its manufacture, may discolor in the presence of acid. " from this website: http://jcsparks.com/painted/pigment-chem.html#FakeLapis