Antique amber and blue glass oil lamp

Three mold font, 2 mold base, two parts can be unscrewed from each other.  No chips or cracks in the glass that I can see. Some straw marks on the base.  Brass connector in good condition. Chimney is old. Embossed burner is good, wick knob is loose but does raise and lower the wick.  Probably from the late 19th century. I can make out two patent dates on the wick knob: 83 and 97, P&A Co. 

18 1/2 inches tall to top of chimney; font width 5 inches.