This is a lower grade velvet obsidian and would be a great one to practice on. Mexican Velvet Obsidian is a higher-quality obsidian with loads of magnetite that creates a velvet-like pattern and flashes within. It often features many colors and works into some genuinely amazing cabochons. It takes an excellent polish and generally cuts fracture-free. They can also make awesome pendants or be great for wire wrapping projects. The color in velvet obsidian is light sensitive. In order to see it, you need to be under bright light, and the stone has to be turned correctly, similar to how a fire opal behaves. With this in mind, this stone is not for everyone and takes some creativity to work correctly.