This is an antique American Brilliant period sugar shaker that is hand blown and cut with notched mitres. The glass fluoresces light green under an ultraviolet light. The piece measures 4 3/4 in height and 3 1/8 in width at its widest. The glass is quite thick with a 1/4 wall at the top (see photos) and is heavy for its size, weighing 1 lb, yet still has nice clarity. The underside is uncut and you can see a polished pontil mark. The glass is in very good condition with an air bubble trapped in the wall and a bit of roughness around the interior top edge. There is a bit of clouding to the interior bottom, but this could be polished away. The metal screw-on cap, however, is in rough condition. It appears to be made with lead content and whatever silver plating was there is mostly gone - also the bottom edge of the cap has small chips to it and there is some corrosion. It would probably be best to find a replacement cap.
Despite the condition of the cap, this is a nice piece of ABP glass - not an often seen shape.