Are there any Islamic legal texts indicating that wearing certain types of gemstones, such as diamonds, may lead to bad events?

This is one of the superstitions and has no basis in Islamic law. Allah Almighty described women saying: ﴿Or one who is brought up in adornments and cannot make his argument clear in a dispute.﴾ Adornments include gold, silver, and precious stones. Allah has also bestowed upon humans and jinn what comes out of the seas and rivers, such as pearls and coral, for He says: ﴿He has released the two seas, meeting [side by side]... From them emerge pearls and coral.﴾ Diamonds and other precious stones are among the adornments that women are permitted to wear, but they should not be visible to non-mahram (definition) men. Wearing these stones is not an omen of anything, and this is one of the corrupt beliefs that a believer should be free from. A Muslim woman should also beware of the arrogance that might affect her from wearing them.