Black Mask Metal Alloy Nail Art Deco Nail Charms. They are 7 mm x 8 mm. The pieces are available in black. They are reusable and can be applied to natural or polished nails. These charms can also be used to dress up other objects like: key chains, jewelry, zippers, and other items. They are very easy to apply and can be done by a nail tech or even yourself. This is a great way to make yourself have a unique look all your own.ook all your own.