This is a Pearl Vise - but you could use it for any awkward, dimensional object that you need to drill a hole in - including stones, metal, polymer clay, and even glass. It centers & holds your item while you drill though a tiny hole in the frame (visible on the left) to drill straight through and into the nylon block (so you don't shatter your drill bit). Hole takes bits up to 1 mm.
A note of caution here - please research the material you are drilling so that you understand the effects of the dust you will be making by drilling a hole and what you need to do to control it. Many items need to be drilled with water or other lubricant to control dust or to keep the item cool. Glass, pearls, malachite, are all items that should be drilled wet.
Made in China. By the each.