Farfalle are made like regular seed beads but when the glass is drawn out of the oven the shape is created by a peanut size metal mold while regular seed beads have been drawn out of oven through a round metal tube.
Generally most colors are created in ovens in processes up to a week. Black and crystal are most common glass and black specifically is used often to clean out the ovens. Technically black is the darkest amethyst possible. Changes in color tone are related to exposure to heat and fire. We have all heard of blue topaz (looks like sapphire) well generally the difference in certain glass is the amount of heat or fire, so topaz glass production may end with so called "blue topaz" glass production as the formulas of heating the glass evolve. So lite sapphire production may eventually turn to cobalt, aqua to Capri and most difficult as explained below hyacinth into Ruby.
Red, Pink, Orange even "nice" purple are hardest glass to make. Red for example in transparent glass, i.e ruby Siam or garnet can not be made in chambers or ovens cause they are sensitive to heat. We have all seen inconsistent burnt red seed beads and off shades of pink these colors are mixed, more by hand, sensitively away from the heat.
Currently natural red and pink farfalles are not produced. It is believed to be technically possible but due the heating process and the more awkward shape it has not been attempted yet, which is why you may see pinks or purples in coated colors not natural colors.
HOW PICASSO COATING IS APPLIED
Picasso, otherwise called travertine (Marble Stone), is a kind of luster. Liquid is mixed in a pot , then beads put in this liquid and mixed properly. Some layer remains on the surface of beads. Then they have to go into oven ( the temperature, is about 400-600 Celsius). Then the beads can be cut or beads remain and as is fully coated like pressed beads.
Beads that are cut, Czech uses term though cut. Cut through the glass. So the base color of bead shows in center and the Picasso is used around the perimeter. Generally this is for fire polish.
MYTH ABOUT TWO CUT OR HEX BEADS, THEY ARE NOT CUT!
Hex is a Japanese term. Two Cut a Czech term. Hex means Six Sided. Regardless, the cuts or sides are created from a metal tube. When the Pixies stick size glass is drawn out of the oven it goes through this tube or mold and the shape is formed as the glass cools. The farfalle is a Peanut Shaped tube and of course a normal rocaille or round seed beads is drawn through a round tube. See this link below for more Czech seed bead shapes:
Metal tubes create all these shapes. Extra facets are applied in a fire polishing process, beads are put on wires then scratched by needles during a wheel churning technique while the beads are hot. The facet's surface is created as it cools. Due to the "wheel" faceting process only beads with center holes can be faceted, i.e. a magatama seed beads or top drilled pressed beads or briolettes cannot be faceted by a fire polishing process. They are top heavy and will break off the wire or a facet at the hole side will destroy the bead.