from the OP my first reaction was porcelain, but I doubt it would go to 1300 °C without a lot of slumping. Almost certainly earthenware, even stoneware would be too high-fired.

Looking at it I immediately saw slip casting, and maybe in one piece. This makes it hollow, even the neck, and essential for lightness. Slip is less dense too. Internal supports and a rib in the head for stiffnes. One curiosity was trying to figure where is was supported in the kiln. The brown is certainly glaze not paint. Domestic ware has little spots where the supports bite into the glaze and are knocked off after. The access hole and the machine head holes are suitable points but that is a long kneck. Maybe sound holes, the fret positions, the bridge and the machine head holes would be good support points if fired supports upside down.

The size of the frets, IMHO would have been fashioned as needed for the height. Ceramic firing is not so precise. One thing about slip casting is there is less inherent stress, but the body (Potters' pun) would have been left to dry pretty much in the mold to avoid introducing stress while green.

Mr Red was a pretty good potter in a former marriage. Wheel, kiln, stoneware, slip-casting, porcelain & 1.5 inch crystals in the crystalline glazes