c1920's Waterman safety pen with gold filigree overlay

I found this pen at a Good Will and didn't know much about it until I rand into the article that had a picture of this pen that he acquired from his mother who said she received it as a gift. I would like to know if I should have it insured and how rare is it. Also it has a cracked I don't remember the proper name for the tip is but I need to find an original to replace it to bring it back to a better quality item. The whole length is 4" inches and approximately 2/3 in width. I like unusual items and so I have a wide taste in what I collect. It will be my legacy to my son. If you could help me I would be very appreciative .