Diamond Peel-Off China Markers,Glass, Cellophane, Vinyl,Metal, Skin, Etc..Assorted - Pack of 12 (Color Mix - 2&times;6 Color) Diamond markers also known as grease pencils leaves opaque markings without skipping on all types glazed pottery, glass, plastic metal, rubber as well as porous surfaces such as fabric, wood, and marks are water resistant and colorfast. can be easily removed from non-porous finishes. using the pull string easily exposes the paper wrapped core.