Swarovski 3400 Corona is a faceted geometric Square sew on stone drilled in the center for sewing. The shape can be sewn like a sequin.
Because it is unfoiled and center hold, the 3400 Corona can be strung and used as a bead to string. The Hematite is coated Hematite only on 1 side. The Other side is Jet Black.
These coronas are vintage stones and their price reflects it.