A bead is a small, decorative object that is pierced for threading or stringing. As an alternative to piercing, plastic beads may be Moulded Onto a Thread during manufacturing; these MOT beads are often used for the throw necklaces worn at Mardi Gras. Beads range in size from under a millimeter to over a centimeter in diameter. Glass, plastic, and stone are probably the most common materials, but beads are also made from bone, horn, ivory, metal, shell, pearl, coral, gemstones, polymer clay, metal clay, resin, synthetic minerals, wood, ceramic, fiber, paper, and the seeds of the Bead tree. A pair of beads made from Nassarius shells that are approximately 100,000 years old are thought to be the first known examples of jewellery.
Beadwork is the craft of making things with beads. Beads can be woven together with specialized thread, or adhered to a surface (e.g. fabric, clay).
Types of decorative beads include:
Size numbers are also used. Unfortunately online vendors will typically not explain the correlation between size numbers and aughts and millimeters.
| aught size | mm diameter | beads per inch |
| 6/0 | 3.3 | 10 |
| 8/0 | 2.5 | 13 |
| 9/0 | 2.2 | 15 |
| 10/0 | 2.0 | 16 |
| 11/0 | 1.8 | 20 |
| 13/0 | 1.5 | 27 |
| 14/0 | 1.4 | 24 |
| 15/0 | 1.3 | 25 |
| delica | 1.8 | 20 |
A hank is unit bundle of strands of seed beads or bugle beads. There are usually 12 strands of 20 inches of strung beads in each modern hank of 11/0 beads. Different sizes and types of beads may be sold in hanks which have different numbers and lengths of strands. Different hanks (age, type, size) have had from 8 to 14 strands, and lengths have varied from 8 to 20 inches per strand. For example, Charlotte size 13/0 cut beads are generally on short hanks, containing 12 twelve-inch strands. Some vintage 18/0 hanks have had 10 strands of 8-10 inches (200 to 250 mm) each.
Czech seed beads are sold from the factories by the hank. They are often repackaged into tubes, bags, or other containers for retail sale, in quantities varying from 5 grams to 40 or more grams. When Czech beads are repackaged, they are usually sold by the gram, which creates some confusion on how many beads come on a hank. Not every 20 inch strand of size 11 beads weighs the same.
A hank of size 2 bugles or size 11 seed beads generally weighs between 30 and 40 grams, depending on manufacturing variations, coatings or linings. Purchasing Czech beads by the hank is usually a better value than the repackaged beads by far.
A production run of a custom made seed bead is 8 kilograms. The beads are produced in the Czech Republic using a 10 kilogram rod of color glass. The excess glass is recycled to form new rods. The color glass rods are produced from a larger mass melt of some 10 metric tons. Formulas for different colors of glass are closely guarded. The recipe for a true black glass was lost during World War I, and modern black glass held to sunlight is a deep purple. Examples of true black glass are circulating in jewelry pieces made to comemerate the funeral of Queen Victoria.
The color of the bead can be transparent or opaque. Transparent seed beads benefit from lining the interior hole in silver, gold, copper. Linings of pink or blue are also common. An exterior coating of a metallic film adds a lustre to seed beads called "AB" - Aurora Borealis.
Glass rods made with concentric layers of color or stripes of color can be used to make patterns of color in seed beads.
Seed bead machinery uses glass rods softened to a red heat, fed into a steel die stamp that forms the shape of the bead with a reciprocating needle that forms the hole. Manual and automatic machinery is in use in the Czech Republic. As the steel dies wear eventually, they are replaced.
Japanese beads are sold by gram weight, seldom by the hank. Buying Japanese beads by the hank usually costs about twice as much, therefore, they are not usually sold or purchased from Japan in this manner.
Most Japanese seed beads are repackaged for retail sale in manageable quantities based on price codes. More expensive beads may be sold in 2.5 or 5 gram units. Standard Japanese seed beads are usually sold in approximately 10 gram tubes. Thus, a 250 gram wholesale package would fill 25 tubes — a bit more than the average beader would need.
One major supplier, Miyuki, sells factory packages which contain up to 1 kg of beads, and are almost always repackaged into tubes or other containers for retail sale. To accommodate the average "wholesale" customer, whether it be a bead shop or designer, some larger distributors have made deals to receive their wholesale packages of beads in smaller (50 to 250 gram) pre-packaged sizes.
Toho, the other major Japanese supplier, seems to have a more flexible packaging policy. Many of the tubed seed beads that can be found in craft stores are stamped with their name on the bottoms, indicating both a wholesale and retail packaging setup.
During the last decade, a new shape of Japanese seed bead, the cylinder bead, has become increasingly popular. Unlike regular rounded seed beads, the cylinder beads are quite uniform in shape and size and have large holes for their size. Because the ends are flat instead of rounded, work created with cylinder beads has a flat, smooth texture. Rows and columns in weaving line up more uniformly, so pattern work comes out more accurate and even.
There are now 3 versions of cylinder beads:
Charlotte cuts are seed beads that have a single facet per bead to add sparkle. These are called "the most brilliant of all seed beads".
Bugle Beads have different lengths but all bugle beads will be longer than they are thick. This creates a tubular shape.
Most contemporary high-quality seed beeds are made in Japan or the Czech Republic. Japanese seed beads are generally more uniform in size, shape, and finish as well as having larger holes than Czech seed beads of the same size. Some seed beads produced in France are available in historic "old-time" colors and are popular for use in repairing or replicating antiquities.