Genuine Clément Massier iridescent lusterware vase from Golfe-Juan, France (late 19th/early 20th century, Art Nouveau period).The Mark on the base clearly shows the impressed/painted signature:"C. MASSIER" (or "CLÉMENT MASSIER") "GOLFE JUAN", the classic, well-documented mark used by Clément Massier on his iridescent pieces. The iridescent, metallic sheen with the crazed/crackled luster surface visible around the mark is exactly how these pieces age and patinate. Massier specialized in "reflets métalliques" — metallic luster glazes using silver, copper, and other oxides fired in reduction to create shifting iridescent colors (gold/bronze, deep reds, magentas, purples, and blues). This vase's combination of purple/blue circular spots, vertical red-purple drips/streaks, and overall oil-slick iridescence is highly characteristic of his experimental lusterware.The organic "drip" and spotted effects (sometimes called flame or feathered patterns) appear frequently in Massier's decorative vases from the 1890s–1910s. The bell-shaped, tapering profile is a common shape in his production. Clément Massier (1844–1917) was a pioneer in reviving and perfecting ancient luster techniques in France. His work from the Golfe-Juan workshop (near Vallauris) had a major influence on Art Nouveau ceramics and even inspired developments in iridescent glass by makers like Tiffany. The piece is approximately 6 1/2" tall and 5 1/4" wide (at base). Remarkable condition: See photos.