Mariamni’s name day is February 17, the feast of Mariamne the Equal-to-the-Apostles.
Churches that follow the Old (Julian) Calendar keep the same feast on March 2 (a day earlier in leap years) of the civil calendar. See everything commemorated on February 17.
The saint behind the name
Mariamne the Equal-to-the-Apostles
February 17, Apostle, Μαριάμνη
St. Mariamne was the sister of the Apostle Philip and shared in his preaching together with the Apostle Bartholomew, travelling through Asia Minor and enduring persecution at Hierapolis. After her brother's martyrdom she continued to preach in Lycaonia.
Also celebrating on February 17
These names share the feast, many of them other forms of the same name:
What to say on a name day
The Greek wish is Χρόνια Πολλά (Chronia Polla), “many years.” A call or a short message on the day is what people remember. See name day wishes you can send and what a name day is.