Dear Mr. Richter,Welcome to Watchuseek. I am afraid that we don't give valuations here but your watch should certainly be "above average". The exact value will depend partly on who exactly the maker was since Tiffany never made watches, they had them made for them. The style of the movement suggests Jules Jürgensen but there were other makers who used this sort of bridge layout too. 1883 sound about right with respect to age (presumably determined by the case hallmarks) - a pity that the expert couldn't identify the maker too.
According to available records Tiffany & Co. did manufacture their own watches for a short period of time. Around 1874, with help from Patek Philippe, Tiffany Co. made their own watches, many with parts from PP, selling them under their own label and unmarked to custom watchmakers. Around 1879, the Tiffany watch making was merged with PP. There were approximately 20,000 watches made. Many are identified as a PP because of the parts used.