Thank you for viewing. This is a dichroic glass (expansion coefficient 90) nugget. The diameter is approximately 1.7 to 1.89 centimeters. I think you can use it for various things, such as making hair ties or pendants. Some of them have small air bubbles. Please refrain from purchasing if you are concerned about this. If you want multiple pieces, please let me know in advance. Depending on the quantity, I will offer a discount and relist them as a set.