Miyuki Delica beads and seed beads all begin with transparent or opaque glass. The glass is treated in a variety of ways to take one base color and end with a limitless array of finished beads. The beads are etched with acid, painted, lined with metal, coated with metal, coated with other glass and shaped in a variety of ways. The following examples show some of the standard categories of finishes that Miyuki uses as well as the abbreviations that identify them.
There aren't as many colors of beads as it seems. Miyuki starts with a fairly small range of transparent glass colors and opaque colors. By applying different finishes and coatings to these base colors of glass, they are able to produce hundreds of different beads.
TR = Transparent
See-through glass bead, with no additional finish.
F = Frosted (matte)
A dull finish on a glass bead, so that it is not shiny.
FR = Frosted rainbow (matte AB)
A matte transparent bead with an aurora borealis finish.
S = Silverlined
A silver lined center to the bead which shines through the glass.
S/L = Matte Silverlined
A frosted glass outside the silver lining of the bead.
An aurora borealis finish over the silverlined bead.
AB or R = Aurora Borealis
A rainbow multicolored finish on a transparent bead.
SF = Semi Frosted (half-matte)
A lighter matte finish, halfway from shiny to matte.
SPKL = Sparkling
A shimmering finish in the same color as the glass.
OP = Opaque
A solid shiny nontransparent colored glass bead.
A solid glass bead with a matte finish.
Matte Opaque AB
A solid glass bead with a matte aurora borealis finish.
A shiny finish that gives the bead extra shine. Often a gold luster.
L or LT = Light
A light version of one color shown in a metallic finish.
D = Dark
A dark version of one color shown in a metallic finish.
An opaque reflective metallic finish.
A dull metallic finish, sometimes with a patina.
The new durable galvanized finish is super durable.
Flecked with earth tones to create a marbled finish.
Using 11-401FR as an example, we see that "11" is the bead size: 11/0, "401" is Miyuki's number for black seed beads, "F" tells you it's "frosted" or "matte", so not shiny. and the "R" tells you it has a "Rainbow" or "Aurora Borealis (AB)" finish.
On shiny beads, the AB finish adds a rainbow shimmer. On matte beads the AB finish usually changes the appearance from a single color to multi-color. So our example started out as shiny opaque black (11-401), then was matted (11-401F), and finally had the AB coating applied which changed the dull black to a multi-hued bead (11-401FR). As the picture below shows, the FR coating can completely transform the appearance.
An additional type of bead is made by applying paint to the inside of the bead holes. This is usually done using clear glass beads and is called color-lining. Since paint colors may not be possible to duplicate as colors of glass, this provides another way to expand the bead palette. Yet another effect is possible by making color-lined beads with colored glass. The image belows shows examples of both styles: