A true "gem" portrait, these c.1700s miniatures are all quite tiny. This one is a painting on wafer only 1 1/4" x 1" oval. It might well be the only image ever made of this individual, and perhaps for some ceremonial or political or military career. I'm not well-versed enough on military costume to determine if his metal-tread embroidery overcoat constitutes period formalwear rather than a military coat. Similarities exist for either argument. Timeframe is easier, as he is c.1750-70s - Louis XV to XVI era. Pre-American Revolution era.
Very good condition for age and type, well-preserved beneath the original convex cover glass and in the original wood period frame. Measurements are noted on the photos. No signature and sadly, no ID.