A shade of deep rich blue on late 17th- and early 18th-century export porcelain, often with gilt (inevitable most worn off). Possible the name derives from Cardinal Mazarin, prime minister of France (1601-62), or less likely, the Duchesse de Mazarin (d. Chelsea, 1699).
Monochrome blue are of several different types depending on how the glaze is made and applied. In principle there are three methods for both coloring agent and glaze - dipping, brushing and (dry and wet) blowing. These three are possible to confuse but I my view Mazarine blue is the specific clear and bright blue that is produced by painting on the cobalt blue with a brush, before adding the clear porcelain glaze.
Mazarine blue is quite unusual and I have never seen this color on anything except the outside of Kangxi bowls of good quality. Often combined with famille verte enamels. On larger objects powder blue seems to have been preferred while on other round objects, dipping seems to have been preferred.