There are several crystals that are believed to promote spiritual growth and development. Here are some of the most popular ones and the reasons why they are thought to have these properties:

1. Amethyst - This crystal is often referred to as the "stone of spirituality" and is believed to enhance spiritual awareness, intuition, and psychic abilities.

2. Clear Quartz - Known as the "master healer," clear quartz is thought to amplify energy and facilitate spiritual development by cleansing and balancing the chakras.

3. Selenite - This crystal is believed to possess a high vibration and promote spiritual growth by helping to clear negative energy, improve mental clarity, and enhance intuition.

4. Fluorite - This unique crystal is thought to promote spiritual growth and enhance mental clarity by helping to balance and align the chakras.

5. Black Tourmaline - Known for its protective properties, black tourmaline is believed to promote a sense of grounding and help block negative energy, making it easier to focus on spiritual growth and development.