When in aveilus can one wear a new, good quality tie that was bought as special to be worn at a simcha? Is shehecheyonu commonly said on a tie anyway?
The reason for the minhag that an avel doesn’t wear new clothing, is because it brings him simcha, therefore only prominent types of clothing are forbidden, such as suit etc. but not undergarments etc. A tie is somewhere in the middle, if it is a regular tie then he may wear however if it is an expensive one that will give him simcha then he shouldn’t wear it.
It is not the common practice to say Shehechiyanu on a new tie, as most people don’t have such spcial enjoyment when getting a new tie.
Y:D 389-3, Mishna Halachos 11-178, R’ Y. Cahen shlit”a