Opal

Opal has been used for centuries as a gemstone. For example, the ancient Romans called it "opalus" and believed that it could bring luck. It was also popular among Native Americans and Australian Aboriginal people who used it in their spiritual ceremonies to invoke visions.

Opal is a mineral composed of silica, oxygen, and water. Its hardness ranges from 5.5 to 6.5 on the Mohs scale, making it relatively soft and easy to form into different shapes. Its physical characteristics vary widely depending on its type; for example, common opal has a milky white color, while precious opal is banded or veined with various shades of color. It also has an unusual property called 'play of color' which results in a unique display of rainbow colors. 

Opal is a powerful gemstone with many metaphysical properties. It has been used for centuries to invoke visions, amplify one's traits and characteristics, and bring luck. Its unique 'play of color' is said to reflect its ability to connect us with the spiritual realms. Additionally, it is believed that opal can help provide insight into our subconscious mind and assist in releasing inhibitions. Furthermore, this stone can also be used as an aid in meditation by helping us access higher planes of consciousness while providing clarity and understanding. With these qualities combined, opal certainly offers immense potential for personal transformation on both physical and spiritual levels.