Is it bad luck to break a crystal?

Answer 1

No.

Naturally occurring crystals are rarely perfect, flaws and inclusions abound, and these flaws tend to make the crystals weak at those points.
In magical work sometimes the flaws are what make the crystal unique and desirable for a specific working.
Sometimes, it just makes them more interesting and pretty to have around... Remember, not everyone uses crystals for magical work

Frequently a crystal is used for protection, if the crystal breaks, it has done its job (protected you from some harm), it might be a good idea to replace it however.

If you break one, that is not part of a charm, by accident, it is not unlucky just inconvenient. If you are a practitioner, I recommend replacing it right away (or as soon as possible) as having one (or more) available means when you are making a charm etc, you can start work immediately and not have to go in search of a new one.

If the crystal was part of a cluster, used for several things, check the "pieces" often single "points" will break free and are good for use in charms and spells. Discard all piece that are severely damaged.

If the crystal belonged to someone else, it is good form to offer to replace it.

Answer 2

In some beliefs, breaking a crystal can be seen as a sign of disrupted energy or a need to release negativity. However, others view it as a chance for transformation and change. Ultimately, the interpretation depends on personal beliefs and intentions.