What is depicted on this small piece of artwork with Mary and the Apostles? Another piece in the belongings of my late grandmother may she rest in peace.

This particular piece is a very beautiful piece in my opinion. This is a part of 7 pieces in total. 

Can anyone tell me what is depicted here?
This is a (very typical) depiction of Pentecost.


  Acts 1:12-14; 2:1-4 (DRB)  Then they returned to Jerusalem from the mount that is called Olivet, which is nigh Jerusalem, within a sabbath day's journey. 13 And when they were come in, they went up into an upper room, where abode Peter and John, James and Andrew, Philip and Thomas, Bartholomew and Matthew, James of Alpheus, and Simon Zelotes, and Jude the brother of James. 14 All these were persevering with one mind in prayer with the women, and Mary the mother of Jesus, and with his brethren. ...  And when the days of the Pentecost were accomplished, they were all together in one place: 2 And suddenly there came a sound from heaven, as of a mighty wind coming, and it filled the whole house where they were sitting. 3 And there appeared to them parted tongues as it were of fire, and it sat upon every one of them: 4 And they were all filled with the Holy Ghost, and they began to speak with divers tongues, according as the Holy Ghost gave them to speak.