My friend is doing a historical research for her uni assignment about the object in the picture attached and would like to know the meaning of the seal. Since neither of us really studies chinese we couldn't figure anything out so far. Maybe someone can help? Thanks in advance for any help you're able to provide :)
So you have identified that that Chinese character is 谱（Simplified 谱 Traditional 譜）。
Based on the picture you posted, I am making my guess.
The picture looks like a pencil, wrapper in a piece of paper showing masks used in Peking Opera, or Jingju（京剧）.
These masks are called 脸谱，and that is where the 谱 character comes from.