Can one make a bracha of Shehecheyanu on a new article of clothing during sefirat HaOmer? On the one hand there is the temptation to say no, since we do not make this bracha between Shiva Asar B'Tamuz and Tisha B'Av as that is a period of national mourning, and Sefirat HaOmer is also a time when we mourn, specifically for the students of Rabbi Akiva. However, Rav Yosef notes that while there is an aspect of mourning to this time period, it is actually supposed to be a happy time, with Ramban even referring to it as a type of Chol HaMoed between Pesach and Shavuot. As such, there should be no issue with saying Shehecheyanu during Sefira.
However, Rav Yosef concludes that one may adopt such a stringency out of piety, although in such a case a person could choose to wear a new garment on Shabbat and make the bracha, since even during the three weeks one could make a Shehecheyanu on Shabbat.