View source for ShuT/Techeleth

Question: may I use techeleth (the blue string) in my tsitsith?

There is a widespread practice in Israel among the "dati le'umi" population,
to wear ''techeleth''.  At first glance, it seems commendable - after all,
there is a Biblical mitsvah to do so!

However:
# There are two main "shitoth" currently used to product techeleth - and there are still others not as popular.  
# A string of techeleth which is not kosher ''invalidates'' the tsitsith!
# Omitting techeleth if it is not certainly available is not a problem
# Only techeleth which has been purchased from an expert is valid

Given that there are multiple, different (and conflicting) versions of
''techeleth'', and that it is a Biblical mitsvah; one must be strict and avoid
using techeleth until such time as we have reestablished the identity of
techeleth beyond all doubt.

{{devar}}