Rare Cobalt Blue Dame-Jeanne are unusual due to their "Cobalt Blue" color. Cobalt oxide base pigment was costly due to its lengthy production process. For well over 100 years, it was preferred ideal UV filter, protecting from spoilage. This very rare and extraordinary collection of jars were in medical or perfume production http://www.brendanbass.com/products/cs3228-31/french-rare-cobalt-blue-dame-jeannes/