This question has bugged me on and off since I arrived in Switzerland but, so far, no-one has been able to give me an answer.

In German (or French, or Italian for that matter) what happens if a new object, condition, illness, sport, whatever is discovered - how is the gender decided?

The other night I was watching a programme on one of the German channels about an archeological dig. One of the team dug up a lump of metal which could have been anything from a bit of an axe to a cooking spoon to a surgical instrument but he knew to refer to it as "sie". How?