The White Peacock, by Dutch master Jan Weenix.
I almost paid a Chinese art company to paint a replica of this one for me (and honestly still might resort to it, eventually.) I've been working in some oil paints lately, however -- as evidenced by the cover for the Beaumarchais Eugénie -- and hope I might eventually get up to the point where I'm capable of copying something as pretty as this.
The main trick I find with imitating old paintings is to be very reluctant in the use of the artificial pigments (the ones with names like "Leaf Green" and "Lemon Yellow.") Before the middle of the 19th century paints were all made from ground up minerals, thus we have paints with names like Zinc White and Yellow Ochre -- these were mineral colors. Red was apparently a very very difficult hue to achieve, and I actually tend to just use the Burnt Sienna in places where red would normally be called for, for best effect. Blue, meanwhile, was attainable but very expensive, requiring Lapis Lazuli to be powdered up for paint. Reportedly, the cost of a painting could be greatly effected based on how much blue was going to be required for it -- that's how expensive it was.