The main problem with the treble has been to get the frequencies of body and cavity resonances high enough and still keep the mensure long enough for a player to finger consecutive semitones without having to slide his fingers around.
At one point we thought we might have to resort to a three-stringed instrument in this range as was indicated by Michael Praetorius in 1619.
A string material of requisite tensile strength to reach the high E 1320 was finally found in carbon rocket wire.
Being the smallest one of the octet, the treble is tuned one octave above the violin. Do not be mistaken by it's size however, this is not a childs instrument. On the contrary, it takes a skillfull player to let it sing it's wonderfull, bright, high tones.