Glassblowing shears come in many variations of size and shape, but the two most basic types are diamond shears and straight shears.
Diamond shears enable the glass blower to cut a section of glass from 4 sides at once, resulting in a cut that comes to a point, which is important when trimming the end of a piece of glass with any type of radial symmetry that needs to be maintained. Variations of diamond shears include different sizes and lengths, and many include a pipe gripping extension from the end of the blade jaws for use in grabbing and guiding blow pipes or punties near the hot end, as when applying bits or handles.
Straight shears cut glass along a line, creating a seam when cutting off a large mass. They can also be used to trim along the rim or lip of a vessel, or to cut straight into the rim, resulting in flap-like appendages that can be further shaped. There are several specialized versions of straight shears, called by various names, including cup shears, trim shears, snub-nosed shears, duck-bill shears, bubble shears and others.
It should be noted that most glass blowing shears will not fare well against cold glass, because glass is much harder than most metals. Cutting glass that has begun to solidify can destroy the shear edges very quickly.
See other tools and equipment needed for glass blowing kits.